Hi Naomiknight87, 

You can't really turn off GST if you have turned it on, but you can set Out of Scope as the default GST so your transactions won't ask you to assign any GST code moving forward. Here is how:

• How do I turn off GST
  • https://quickbooks.intuit.com/community/GST-and-BAS/How-do-I-turn-off-GST/m-p/263106#M21

Please let us know if you have any questions.