What is the best way to remove wallpaper border?

Usually a spray of warm water or steam will loosen the glue.

I use 50/50 mix of vinegar and hot water. Spray the border, let it soak in, use a putty knife to scrape off. Wash the glue residue with vinegar and water.

Make a mixture of water and fabric softener 50/50

Have you tested the border to see how easy it will come off? Sometimes you can remove it just by grabbing a corner and pulling gently. If you get resistance, then get a spray bottle with warm water and spray it down, let it sit a moment, then peal or use a warm, wet rag to loosen and pull wall border off. If it is really stubborn than take a fork or knife to score (make cuts) in the border, spray again with warm water, and proceed again with either pulling or rubbing off with a warm wet rag. You can also add some liquid Dawn to the warm water to help facilitate faster removal.

I agree with the mixture of fabric softener and water. It works very well and smells good too. Sometimes the old paper needs to be scored with a "paper tiger" or simply using a paring knife lightly to cut through the top layer of paper.

Fabric softener works well to remove wallpaper