Go to Dimension Combinations

Click on the dash after the Name Limited

 
There are three options:
No Limitations
Limited (setting the limits)
Blocked (everything is limited)



Select Limited
 
To set the limitations – select the word Limited
You will get this message

Select Yes
Once again select the line to set the limit

You will get this message – select Blocked to limit the use of the dimensions

The combination is now Blocked