This is just a couple of additions from this tut:
Above tutorial is for E92. For the E90 its basically the same I just wanted to add a couple of helping hints.
The two tabs on the back are covered by a chunk of black plastic preventing you from just 'lifting' the two tabs out like they do on the E92. All you have to do is push up on the whole black plastic 'chunk' and it will pop and release from the bumper cover. Do that on both sides. Once 3 bolts on each side for the fender wells are remove plus both bolts on each side holding the bumper cover corner, push in on the corner of the bumper cover (pick a side) nearest that single bolt and push inward toward the car and then pull out a bit. It should release the first hook. Once that is done, put your hand on the wheel well part of the bumper cover and put your other hand on the back of the bumper cover near those two rear tabs and yank backwards with decent force a few times. This will pop the bumper off. I hope this helps someone. I didn't break a single tab and got it off very quickly this way. Breaking tabs happens when you try to remove each tab individually by pulling outward away from the car instead of straight backward. When you pull straight back, you aren't stressing the thin area of the bumper cover and because the hooks are rounded, it will remove itself.