In my experience the rose anems will move pretty quickly once you do what is suggested above, point a power head at them, and they start to move pretty quick, once they the foot swells up and it starts to walk, just peel it off and put in a container for removal. The RBTA is well known for being a wanderer, so if you get it loose and move it to another part of the tank, it will move itself around, I assume you want to remove them...
The last time I took one out, I put it in a bucket over night (by sure to heat the water and have a little flow) :).