How to Disable Outlook Add-ins For Troubleshooting

Step1: Starting in Safe Mode will tell you if one of your add-ins is the problem, but if you want to disable a single add-in
such as one that’s just been installed or a core Microsoft add-in that isn’t disabled in Safe Mode
you can do that too. Click File > Options, and then click the “Add-Ins” category on the left. 

Step2: This will open the Add-ins section. To enable or disable add-ins, make sure that “COM Add-ins” is selected in the dropdown
(it’s the default, so you shouldn’t need to change it) and then click “Go.”

Step3: This opens up the COM Add-ins dialogue, where you can enable or disable add-ins.

Step4: Enabling and disabling is a tick-box exercise—a tick means the add-in is enabled; no tick means the add-in is disabled.
To disable an add-in, untick it and then click “OK.”

Important: Make sure that you don’t click “Remove.” This will uninstall the selected add-in, not disable it.

Step5: When you go back into File > Options > Add-ins, the add-in you disabled will be visible in the disabled add-ins section.

The add-in will remain disabled until you enable it again. Test to see if your problem occurs when the add-in is disabled; if it does, keep disabling your add-ins one by one until you find the culprit.

Credit : https://www.howtogeek.com/411900/how-to-disable-outlook-add-ins-for-troubleshooting/