- Turn the chair upside down on a desk or on the floor.
- Use small scrub or tooth brush or mascara brush/wand, and clean the caster with soap water or alcohol. This will remove dusts and keep only hairs and threads that got tangled.
Remove the visible hairs using butter knife on the crevice of the caster on both sides. Kitchen Tweezers are very helpful here.
Use nail clipper/cutter's bottle opener. It will have pointed curve. Insert it into the fissure, Catch the hairs and pluck off the hairs. Keep revolving & rotating the caster strategically by other hand while doing this and this will help the tool to catch more hairs.
Simply cut a section of duct tape and then stick around the cover and pluck off. You can also cut a section of duct tape and fold it back around your razor knife so that it will be like a closed loop ready to stick, then insert it under the wheel cover and pluck off. Reason why Razor knife is because they are very thin.
Do not use sharp knives including razor knife. It will cut the hairs and make it difficult. But if the hairs are very stubborn and likely to tangled like a closed loop, cut the hairs with small manicure scissors or razor blade to break the closed loop.
If you are not satisfied after trying the mentioned workarounds, then I would recommend you to get a screw driver and remove the caster from the chair, then wash on the soap water and apply lubricants.
The example sample images are taken from Google search