If you can't deactivate a serial number you have to contact the Adobe support. Only they can reset the activation counter.
This is a public forum and not the link to Adobe support. We're all normal users as you are.
Sorry, nobody here can help with an account or payment problems
Be sure to be signed in with your Adobe ID before accessing the link below.
Do be aware that Adobe's staffing is also impacted by the virus and so wait times can be a little are longer. Make sure that your browser does NOT block ads, scripts, or pop-ups.
Please allow 'cookies' in your web browser for the link to work
This link will go directly to the chat option
Type "Agent" in the chat box to bypass the chatbot and be connected to a person
-Meaning type in the word Agent without the quote " " marks
https://helpx.adobe.com/contact.html?rghtup=autoOpen
ASK ONLY FOR ACTIVATION SUPPORT TO ADJUST YOUR ACTIVATION COUNT
You may have to be PERSIST or TRY SEVERAL TIMES to find a more experienced support professional.
My System: Intel i7-8700K - 64GB RAM - NVidia Geforce RTX 3060 - Windows 11 Pro 26H2 -- LR-Classic 15 - Photoshop 27 - Nik Collection 9 - PureRAW 6 - Topaz Photo AI