Having too many categories is messy - because the top horizontal menu already have it. So you might want to remove the one in the footer which is unnecessary. How to do it?
1. In prestashop admin page
2. Go to Module and Services>>Positions
3. Look for Display Footer section and under that there is "Categories Block" and unhook it.
Next time you want to hook it back just click on the transplant a module and find "Categories Block" and hook it back. Make sure you hook in the footer section again if you want to.