I used to be a caretaker at an infant and primary school.

We had plenty foxes which I had to deterr for obvious dangers of safety and hygiene to the youngsters. Here are some of my methods.

1. Make sure you block up all runs. Use wire concrete especially go below soil level so they can't dig threw. Check and check again. The harder you make their journey they will go elsewhere.
2. Use brambles. Foxes hate brambles and thorn bushes. Use these to block up all holes in fences. Grow them close to a fence. Also use chicken wire. Wire this to the top of fencing so it is proud.
3. In a home garden I make sure all fences are well covered with shrubs and climbing plants e.g honeysuckle, climbing roses. The foxes are then unsure of their route over a fence. Make fences are high. Add chicken wire extension.
4. Remove all items close to a fence e.g. water butts that will give them a leg up.
5. Use human urine in a garden.

Hope this is useful