SharePoint: How to change document library owners
Follow these steps to change document library owners. These directions review how to add or remove a user.
Step 1: Access your document library. Select the gear icon in the upper right-hand corner.
Step 2: Select Library Settings.
Step 3: Select Permissions for this document library.
Step 4: Select the group whose ownership you want to remove. Select Remove User Permissions.
Step 5: To add a user, select Grant Permissions.
Step 6: Enter the users name, select share everything in this folder, even items with unique permissions, select Share.