I wouldn't recommend it without discussion
There was a period of a few years that one of my groups had a rotating DM. During this time, we generally didn't step on the toes of previous DM decisions.
This was for a couple of reasons:
- That person would DM again and we didn't want to create a series of changes going back and forth.
We didn't hand out any homebrew items, either, so that may have been part of it. But overall, we left decisions and storyline points in place to keep the continuity from one DM to the next and to allow people to reference back to previous portions they had DM'd.
In your case, it's not clear what the item is or how it was changed, but retconning items can be problematic.
There wasn't a case where we needed to do this, but if there was I would have begun it as a communication and discussion around my concerns and made it a table discussion at the minimum between the item owner, the previous DM, and myself.
Retconning without communication can very easily lead to unhappy players, which is the one thing we all try to avoid.
Raising concerns quickly
If another DM is concerned that an item is going to cause a problem, it's best to bring it up immediately once the item is announced. This gives everyone a chance to discuss the concern and alleviate potential problems before the item becomes in-use and the player has acclimated to having it.
But as DM, they can if they want
As stated above, the problem may lead to player dissatisfaction and eventual departure. But ultimately, the DM is the final arbiter - it's up to the players if they're okay with the decisions the DM makes and if they want to continue playing.