This article is my take on shaving off details (pockets, holsters, badges, etc.). My method takes longer than the "just lop it off" method. However, I feel this way is less work in the long run.
For my example I will be removing a holster.
Step 1
A cross section of a leg-with-holster will look something like this:

Some suggest making one quick cut to remove the holster like this:

Step 2
As you can see, your figure will have a dent in his leg. Since repairing the dent means more work later I suggest "shaving" the feature off with a series of tangential cuts (always cut AWAY from your body!):
Step 3
Do as man of these as you find necessary. for something as large as a holster I would suggest at least five cuts.
Step 4
Sand down any bumps.
Step 5
If you need the feature saved for some reason (let's say you want to put the holster on another figure) make a mold of the feature (then you can have as many as you like!) and just shave the feature off. I have tried several times to "peal" a holster away so I could have it and the leg intact. I have always ended up ruining the leg and holster and slicing my finger up nicely to boot.