Do you mean that you want to stop certain seller’s items from appearing in searches?
If so, you should be able to set up a search and save it.
You may need to switch to Advanced, to the right of the big blue Search button top right of the eBay home page.
You can block selected sellers from the search results.
Edit the search subject when you want to search for any other item and save it again.
https://www.ebay.co.uk/help/buying/search-tips/saved-searches?id=4051&st=12&pos=1&query=Saved%20sear...
