How can i kill a tree slowly thats in the front yard and very tall

Drive a copper nails in the tree...can get at any hardware store. copper you can get it at any hardware store.

Drill a bunch of holes all around the circumference of the trunk, and put Roundup in the holes. It will be absorbed into the tree's system, and you will need to keep refilling the holes as it is absorbed. Angle the holes downward, and make them as deep as you can, so that the holes will hold more Roundup.

Shereeberry57, since you want the tree eventually dead, I suggest you contact a professional tree removal service to come and take the tree down safely and completely. Once you have a tree that has been weakened, it becomes very dangerous to your property and lives. Better safe than sorry!

I agree with drilling angled holes around the tree. Fill the holes with salt and add a little water. May need to repeat. It will slowly dry out and die.

If you drill holes then it will take some time but do the trick, best of luck :)