If for some ODD reason you want to disable Intellisense in SQL Server Management Studio, there is a very easy way to do so.
How to Enable or Disable Intellisense in SSMS
Open SSMS – Click on Tools, Options, Expand Text Editor, Transact – SQL, and then click on Intellisense (check screenshot below)
It’s as simple as that! If you are trying to enable / disable to refresh the Intellisense cache because you have the red squiggly underline in your T-SQL, check out my post here to show you an easier way to refresh your Intellisense cache in SSMS.