All my friends and acquaintances know I quilt. Many have "gifted" me w/fabric and UFO's from family members that have passed. I have started letting them know I will keep what I want and will use and will forward the rest to others that will use them or donate to a Goodwill type place. I ask if that's ok and if so then I take the fabric and if not I think them for thinking of me and decline the offer. I've learned the hard way to take things w/the vague thought that I'd return the "favor" by doing something for them.
As for the "permission" part of getting rid of things I've had to VERBALLY tell myself I have permission to get rid of specific things. Once I started doing this it's gotten easier to let things go...