When you use the Remote Desktop Connection tool, the the computer you connect to is added to the Remote Desktop Connection Computer dialog.
There is no standard way to remove entries from this list.
To remove entries from the Remote Desktop Connection Computer dialog:
1. Use the Registry Editor to navigate to:
HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Default
2. Select the MRUn Value Name, a REG_SZ data type, that contains the IP Address or <ComputerName.DomainName.DomainSuffix> string of the entry you wish to delete, right-click it, and press Delete.
NOTE: Every new entry is named MRU0 and the previous entries are renamed by adding 1 to their number.