When you delete (uninstall) KineMaster and reinstall it, all your KineMaster projects will be deleted too.

To keep KineMaster projects, you must back up the projects you want using Export as .kine file (KineMaster >> Tap Create on bottom right of the screen >> Tap three dots... for project menu >> Export as .kine file).

Please make sure the .kine file is not saved inside KineMaster folder.
On iOS: Change from ‘KineMaster’ folder >> choose ‘On My iPhone/On My iPad’ and save it in any other folder
On Android: Choose any other folder than ‘KineMaster’

After reinstalling KineMaster, you can restore the backed up projects tapping Create on bottom right of the screen >> Create New and using the Import button on upper right.