Click “Merge” on the page of the tag you want to keep, then select any tags that should be removed and merged.
If you click the big blue “Merge” button at the top of a tag’s details page, that tag becomes the target of your merge request. In other words, any additional tags selected in the edit request form will be absorbed into that initial tag. Always merge into the tag you intend to keep. Often it will be the only “sorted” tag in your merge with a category and/or definition assigned to it. If you are merging previously “unsorted” tags, your preferred merge target is usually the most frequently used variation (meaning, it has the most scenes attached). Also please note roughly how many scene entries a tag has in your edit comment before merging. There is no easy way to find these numbers after a merge and they are often taken in consideration when choosing primary names. If you would prefer to change the primary name of the tag as well, it is best to save that for a separate edit after the merge is approved.