** Attempt this at your own risk, I accept no responsibility for any injuries or loss as a result of these suggestions**
I have cut the springs on several vehicles, the last of which was my 84 rabbit. It has similar front suspension as a metro I believe(single control arm/macpherson strut). The back however; is a twist beam with a coil over shock. I believe the metros have independent rear suspension, Im not sure whether its a strut/spring combo or what. For the integrated strut spring type suspension most people remove the whole assembly, compress with a spring compressor, dismantle, cut the spring, compress, reassemble, then see if its ok.
I have found that you do not have to use a spring compressor in most cases.
Last time I removed struts I removed the nut at the top of the strut while the car was on the ground. This is the one that goes through the strut mount. I then jacked up the car and the suspension drooped, put the car on jackstands. The spring will completely relax and the strut shaft will come out of the mount. Leave the mount in place on the car unless it is shot, if its bad replace it. A bad mount usually can be identified by a clunking sound whenever you go over bumps. Make sure that the spring is not still compressed before you unbolt the bottom of the strut. If it is you may have parts shooting all over. you can unbolt the bottom of the strut and pull it out now. The spring will be seperate from the strut and is ready to cut. I usually start with 1 coil and usually end up taking another half to whole coil off after that. I would suggest you take a half a coil at a time to make sure you dont lower it too much. If your spring is not a constant diameter spring you cannot cut it and have it stay in place afterwards. If only one end tapers so that is will sit flat in the spring perch cut the end that does not taper. If both ends taper you will have to bend the spring afterward to ensure that it will sit flat on the perch. I heat it up with a torch just enough to soften the metal a half a coil from the end I cut and bend it so it will sit flat using a large wrench. DO NOT QUENCH THE METAL AFTER HEATING. Let it cool as slowly as possible so that is will not become brittle. After this is all done put the spring on the strut and bolt the bottom of the strut in place. Guide the strut shaft back into the mount as you slowly let the car back down. you could also jack the suspension up to compress the spring again, rather than just letting it back down. THIS IS A POTENTIALLY DANGEROUR JOB ATTEMPT AT YOUR OWN RISK
Another method I have used is to jack up one corner at a time till the suspension is completely drooped(tire off the ground). I then pryed the spring out if the perch with a crowbar and cut off a half a coil at a time with a pneumatic cut off disc till I had cut off a coil and a half. I let the spring relax back into place and then muscled it around till it sat correctly in the perch. all 4 corners took about a half hour total.
However you lower the car you will probably have to trim a little bumpstop off if you hit them often or if you can see that there is very little travel left before contacting the bumpstops. trim as little as possible.
Anytime you cut a spring the spring rate will increase slightly
Most production cars have a little bump steer which means that the tires steer in or out as the suspension moves up or down. This means that if you lower it you likely have changed the toe, you either have more toe in or toe out(fronts of tire closer together, farther apart respectively). You will probably have to get an alignment to correct this, or just wear your tires faster.
If you have stock or stock replacement struts you will blow them out quicker when the car is lowered. The best way to control the suspension on a lowered vehicle is with a stiffer shock/strut. There are aftermarket struts/shocks specifically valved for lowered vehicles. You might have more of a bouncy ride if you lower your car too much on stock struts because they are unable to dampen the inputs to the suspension and you now hit the bumpstops more often. If you dont go overboard in lowering on stock shocks/struts you will not have a problem and your handling will likely improve.
It is not a good idea to lower a car more than where the lower control arms are parallel with the ground. If you do you will possibly gain positive camber more easily in suspension travel, and your roll center will be too low. Lower control arms Parallel with the ground is the ride height to shoot for for performance.
Here are a couple lowered cars I have done. Every car is different so cut a half a coil at a time.
a coil and a half front and back
Coil and a half front and back
2 coils front, 2" lowering blocks back
and just for fun, no springs at all, sitting on the ground