Booking Manager portal allows you to remove charter operators from the search results. Once you log in to the portal click on My Partners (1.) to open the entire list of charter operators.
Once My Partners list opens, click on the partner you want to disable in the Available partners list (1.) and click on Display partner button (2). to display Partner details on the right. Then place a check on Disabled as my partner (3.) and click on change button (4).