You can only remove Multiplay.co.uk from your server name or change the server graphic if you purchased the De-branded option with your server.
If you didn't purchase this option but would now like it you just need to go to your Clanforge and select the Account Upgrades option, in here you will find an option for changing between branded and de-branded.
Changing the server name
This couldn't be simpler, in Clanforge -> Edit Profile -> Settings, you should see a text box "Server Name" and the current server name filled in, you just need to edit this and click either Save or Save & Apply (Save & Apply will restart server to take on the changes whereas Save will save and let you manually restart the server).
Changing the welcome message
Some games support a “welcome” message this can generally be found in your servers config either a separate file e.g. MOTD.txt for CounterStrike or as a variable in the main config file or Setting.
To change go to Clanforge -> Edit Profile -> Settings, change the relevant option and click Save or Save & Apply, your server will now start with the new message.
Changing the server graphic
Some games support a “server graphic” this can be found in your servers config e.g. sv.sponsorLogoURL and sv.communityLogoURL for BattleField 2.
To change go to Clanforge -> Edit Profile -> Settings, change the value and click save. Your server will restart with the new graphic.
Note: The BattleField client caches images permanently so to update the graphic you need to change the name of the file.