What’s the worst that can happen if you leave a hard restriction in on departure that gets in your way later on? The a/c attempting to level off earlier than you might like which is easily rectified, no harm done. Especially if you keep the FMAs in your scan.
If you delete something that was or became relevant, you are increasing the possibilities of a) a level bust, b) a TCAS event and/or c) an Airprox or worse.
Looking at those two alternatives from a risk PoV, which would you rather have...?