Hi enaj
If you cut them down to just above grond level, then drill holes in the stump that is left put some root and stump weedkiller in the holes, the one I use is "Deep Root treestump & weedkiller" it is biodegradable, and you need not keep children and pets away from the area,
Once you have put the weedkiller in cover with a plastic bag to stop rain getting in, it will take a while but it works, the other alternative is to call out a specialist stump remover but that will cost quite a bit, Good luck, Ray