Clear all of the lower branches from the tree with a chainsaw and position the bucket of the track-loader as high up on the tree's trunk as possible.
Push the tree over with the front bucket of the track-loader.
Dig out the major roots of the tree with the track-loader.
Cut off all of the major branches of the tree.
Use the track-loader to pick up the stump end of the tree and wrap a chain around the tree so it can be pulled.
Attach the chain connected to the tree to the track-loader and pull the tree out of the pasture.
Fill in the hole left by the removed tree with dirt.