Hi,
You can edit the destination in transaction SM59 and modify "Path Prefix".
Depending NW version the destination cannot be edited , you may have to delete and recreate it manually in SM 59 with same HTTP Destination (GUID) from soamanager.
When you edit /add path prefix and save the HTTP destination , you will receive a warning message.
"Query string not allowed"
Just force it by hitting "Enter" key .
Thank you
Regards
Goverdhan Totawar