ON MOBILE:
in the top right of the post and select Remove Tag.
See also: How to Remove Someone Who Likes Your Facebook Page
ON WEB/BROWSER
on the upper right hand corner of your Facebook page3. On the drop-down menu, click on Activity log
4. Click on Posts you're tagged in at the left-hand side of the page
5. This will pop up a screen that shows all the posts you've been tagged in, scroll through and select the post you want to untag yourself from by clicking on the pencil icon by the right of the post



