Place 4 tripmines in the same spot and set them to automatic respawn. Hit 'x' and 'y' i really fast and you should throw them really quick, just wait till you have a massive pile of tripmines and they should blow up by themselves.
...and if you want them permanently out, you have to physically block them with immovable items like double blocks, double walls, etc. Use the turret trick to get past the invisible wall right next to the towers.