Usually in the Windows remote desktop, if the session is full we have to wait for other user to logoff.
but sometimes we need to go to remote desktop immediately and can not wait because an important thing.
If you need to force, follow this trick :
1. Open Run Command dialog by pressing Windows+R key.
2. Then type the following command :
mstsc /console /v:nameserver or ip address of remote computer
for example: mstsc /console /v:192.168.0.10
mstsc /console /v:nameserver or ip address of remote computer /admin
for example: mstsc /console /v:192.168.0.10 /admin
3. Click OK