Please follow the steps below in order to make the Customer or Supplier inactive:
Select the Customer or Supplier you would like to make inactive.
Select Edit at the top of the screen.
Select Info at the top of the screen.
Select the Inactive box within the window which opens.
Close the window which has the inactive box in.
Select Save to finish.
If you're using Access Office Integration then this is also a process that can be carried out using this method.