If you want to show/hide Hold events when scheduling time to meet, so it doesn’t crowd the main calendar, you can add a separate Outlook blank calendar, (ex Proposed Meetings) and set it as the destination for Hold events.
1. Go to Outlook "Add calendar" and "Create blank calendar". You can name it anything you want.
2. Then go to https://freebusy.io/app/integrations and set it as the destination for Hold events.
You can’t turn off Hold events completely because they are used to store data about the poll/suggested times in your calendar while the meeting is pending. We do this to minimize the amount of customer data stored in our system which make it easier to be compliant with a variety of security and privacy policies.