How to dismantle a chair caster?

I have recently purchased a secondhand office chair but the casters will not turn easily. They are all tangled up with hairs. I have removed the caster bodies from the chair and attempted to cut the the hairs away with a craft knife without much luck and am wondering if it is possible to remove the wheels from the assembly so I can do a proper cleanup job. I am loathe to use a scewdriver and brute force and would welcome any advice you can give me.
Thanks