Are you sure they're glued on? The easiest method to remove really grippy rubber that *seems* glued to the handlebar is to use a thin tool to pry a little space between the grips and bar and squirt in some 91% isopropyl alcohol.

A good thin tool that won't damage the grips can be made by cutting some plastic from a blister pack of pretty much any household item. Or cut a strip from any plastic bottle. Cut a strip about 1/2" to 1" wide and a few inches long. Deburr any ragged edge to minimize damage to the grips -- a kitchen knife or scissor blade scraped along the burred edge of the plastic strip will do. Insert the strip between the grip and handlebar -- this should reveal whether it's really glued or just a very snug friction fit.

The plastic strip will curve to match the grip and bar -- squirt some of the 91% isopropyl alcohol into the trough, give it a few seconds or minutes to work, then see if it's loosened up any. Even if it's glued, this should loosen some glues -- I doubt they'd use any adhesive that would require a strong solvent or heat to remove.

Also, I see from the Linus website they sell leather grips. They might be able to tell you for certain whether the grips are glued on, and how they'd recommend removing the grips.