The goal is to deter foxes, not harm them. With that in mind, the RSPCA recommends humanely deterring foxes by using bird feeders designed not to spill food onto the ground, protecting fruit and veg crops with solid weld-mesh and promptly clearing up any fruit that falls from your trees.
Fish, blood and bone fertiliser can also attract foxes, so consider switching to a plant-based product. Additionally, securely seal dustbins with clip-on lids and never leave rubbish out in bags that foxes can easily break through.
If a fox has already made its burrow, it's best to wait until after the cubs have left the den in late summer, before actioning any of the above deterrents. You can encourage the mother fox to move her cubs by making noise and walking nearby. Once she's moved on, take the above recommendations to deter her return. Remember: it is illegal to poison foxes.