In the Translation Memories view, make the translation memory you want to close the active translation memory.
In the top-right corner of the TM side-by-side editor window, click 
Close Document.
This topic describes how to close a translation memory in the Translation Memories view. This closes the TM side-by-side editor window but does not remove the translation memory from the navigation tree.
To close a translation memory:
In the Translation Memories view, make the translation memory you want to close the active translation memory.
In the top-right corner of the TM side-by-side editor window, click Close Document.