Is permanent vinyl removable?

Removing Permanent Adhesive Vinyl
Most any vinyl can be removed from glass or other surfaces using a little heat and a scraper.  Heat should be as simply as a hair dryer or parking a car in the sun for just a bit.  We advise against using a heat gun unless you are very skilled because quick temperature changes can shatter glass or scorch underlying paint.   If adhesive residue is left behind a simple product such as Goof Off or Goo-Gone can be used to remove it.  In extreme cases it may require a rubbing compound and a buffer.  If any vinyl is applied to paint such as on a car, when removed there is a possibility of it leaving a darker spot under the vinyl since it protects the paint from UV exposure.  

If you can remove it, why is it called permanent?
When people hear the word "permanent" they think in terms of something that can never be changed such as an engraving or etching.  Permanent vinyl is actually "Permanent Adhesive Vinyl" and the overall product (vinyl and adhesive) is rated for a certain estimated lifespan outdoors in the elements without peeling and cracking under most conditions. The adhesive is pressure sensitive and when applied properly the curing process is activated by pressure and typically after being applied to a proper surface the adhesive is fully cured to a cement-like state.  Extremely harsh conditions can shorten the life a bit but these films are designed to be used in outdoor environments. Typically in extremely harsh conditions of places like the Winters of Maine versus the Summers of Arizona, it will last several years. The vinyl is generally considered permanent unless something removes it.  For example, if you write on a window with permanent marker it's generally going to be there unless an outside force removes it.  Just because something removes it doesn't mean it's not "permanent".  For that matter, car on a paint can be removed by an outside force but that doesn't mean it's "temporary paint." 

Why are some films called "Temporary Vinyl"?
Other films labeled "temporary adhesive vinyl" are intended for indoor use where exposure to the elements is not a factor and can generally be removed from painted walls without harming the paint.  In this case the adhesive is usually a "clean remove" product.  That said, if paint is not adhered well to the surface it could still peel the paint as any sticky substance could, but it is less likely and simply means the paint was of poor quality or not applied to a proper surface.