After you remove a custom dictionary, SDL Trados Studio does not use that dictionary for spell checking.
To remove a custom dictionary:
Select Tools > Options from the menu bar. The Options dialog box is displayed.
Select Editor > Spelling from the navigation tree. The Spelling settings are displayed on the right.
Click Custom Dictionaries to display the Custom Dictionaries dialog box.
Select the custom dictionary and click Remove.
Click OK until you have exited the Options dialog box.
The dictionary is removed from the list of dictionaries.
Removing a custom dictionary does not delete the dictionary, so you can add it again. See Add an Existing Custom Dictionary.