I purchased element premier element 2019 for video editing how to remove the trial version

If you mean you are prompted the Trial dialog that is prompted every time you launch the product, that mean product is still not serialized and activated. You will need to enter the serial number and Sign in. After this if your project is still showing the Trail bar on the program monitor, you can get rid of this by clicking on the menu Timeline > Delete Rendered Files for all projects.

You will need to render again wherever you feel so, but nothing in the projects will be affected and Trial bar would be gone.

Go to the directory folder where you .prel project files are stored. Delete the folder Adobe Premiere Elements Preview Files.