Linoleum is a floor covering which is usually made from renewable materials such as solidified linseed oil, pine rosin, ground cork dust, wood flour, and mineral fillers such as calcium carbonate.
Over time, if you decide on changing things up a bit by laying ceramic tile over your existing linoleum flooring, it is always best to first remove the linoleum and as much glue as you can from the floor. Take note that linoleum is not a good substrate for tiles.
Laying ceramic tile on top of any “soft” floor covering like linoleum is never a good idea. One way to remove the linoleum is to scrape off as much linoleum cement/glue as you can with a metal scraper.
However, if this sounds like a bit too much work, you can just scratch it up with a belt sander once and then use a palm sander another time.
It is also best to vacuum up the loose materials, then just apply the steps explained in our earlier posts for laying ceramic tile and let them dry. If there is a need, you can also apply a waterproof treatment. The key thing is to let each stage dry thoroughly before adding the next item.
It is important to remove the linoleum else when laying ceramic tile, the new tiles will rock/wiggle slightly after the job is done and you will have continual cracking of the applied grout.
Lastly, if removing linoleum is still too much to do; the last option would be to use cement boards as a base. It can be used right over the existing flooring, if you wish. Personally I would remove it when laying ceramic tile, though.