Removing window film can be a very easy process, but it all depends on how long the film has been on the glass, it's exposure to direct sun, and the type of film that was used. You will need:
We supply window film removal tools which you can purchase online.
Here's a video tutorial which shows the basic principal. To make the work more manageable, wet the surface of the film with a spray bottle to act as a lubricant and first score the film into narrow strips with a sharp knife. It is much easier to tackle window film removal in small strips especially if the film has been applied to the glass for a long time.
Typically, window films are either made of PVC (vinyl) or PET (polyester), and most are self-adhesive.