"Office Workers Demand More Parking" in SimTower

Some walktrough guides advise you to ignore this, so the message you're having may be true be there is nothing you can do about it (and I haven't found any patch to correct this.

To upgrade to "Tower" you will need 15000 population and wait for a wedding to take place.

To achieve 15000 population you will probably need to erase some condos slowly and build offices until you ran out of stairs (because using some stairs to offices levels will help).

If you're bankrupt deleting condos just wait until all offices are re-rented. Lower the prices of some of them don't rent at all.

It can take a long time to achieve it, but then you'll see it in the cathedral if I remember correctly. Good luck !