You can remove any translation you created. Read here how to do it.
How to remove a translation
Navigate to Confluence administration → Manage app.
Use the search bar to look for "language pack".
The language packs you created and installed will have the name "Language pack for [project name]".
Click on a language pack.
Click on the Uninstall button. Then, click on the Uninstall app button to confirm the deletion.
Link to this page: https://seibert.biz/manager-deletelanguagepacks