Lower control arm I assume you mean lower suspension arm, pretty sure they're one in the same.
There is loads of info out there about this so by all means search you may get a more detailed reply.
Essentially it is held to the car with just 5 bolts - 2 at each side on the chassis and one on the ball joint for the hub carrier / upright.
Its a bit of a fiddly ass job unfortunately and a lot to learn the first time you do it so allow yourself plenty of time.
You're going to want to soak the bolts on the chassis side in some penetrating oil over a period before trying to get them off. When I first attempted it on my 156 the bolts were seized solid to the point I actually snapped one of them in half (and they ain't small bolts!). If you've got a windy gun and compressor that'd help too.
Essentially you're going to want to:
- Jack front of car up and place on axle stands
- Remove both front wheels (to keep the balance on the ARB across the axle for next step)
- Remove anti roll bar link on affected side (disconnect from suspension upright if needed but best practice throw away and replace as they're only cheap).
- Remove brake discs (which means calipers and carriers come off too)
- Remove large bolt running through lower arm that hold suspension strut
- Remove nut from bottom ball joint on suspension arm and release ball joint (ball joint = PITA, hope you've got a good splitter as the fork type don't always fit) so you may have to beat the crap out of it.
- Remove upright / hub carrier top arm ball joint - will allow you to articulate the upright and get it free from the lower ball joint.
- Remove bolts securing lower arm to chassis
From memory (although a year or three since I've done it) that should get the old arm out and off.
Replacing is a bit of a fiddle as the rear mountings of the lower arm sit under the ARB mounting point and the ARB forms the nut for the bolts, so you need to sort of lift the ARB and wiggle the bottom arm under it and get it lined up again to secure. It'll make sense and be much easier the second time once you've done it and understand it the once!
Last word from me - these things are better changed in pairs and given how far you've got to disassemble stuff consider changing top arms and drop links at the same time (if not replaced more recently). You WILL need to have the wheel alignment checked once this is done too otherwise you'll mess your tyres up big time and the car may handle rather weirdly if they're out of alignment.
1999 156 1.8TS Sport Pack 3
2001 166 3.0 V6 24V Super
2003 156 GTA 3.2 V6 24V
2005 156 1.9 JTDM-Jet Sport
2008 159 1.9 JTDM Lusso
1997 GTV 2.0TS Lusso
2001 147 1.6TS Lusso