You have some proposals that you would like not to acknowledge and FreeBusy Scheduling assistant sends you a mail to “Accept & Add to Calendar”; you would rather decline this meeting proposal and possibly inform the proposer why this meeting to decline.

Step 1: Go to FreeBusy.io

When you get a proposal for a new meeting you receive it as a new meeting proposal in FreeBusy sidebar which you can acccess from belll icon on freebusy.io website.

Step 2: Click on bell icon to open pending proposal sidebar.

Step 3: Find the proposal that you wish to decline and click on "Decline"

Step 4: (Optional) Add a note for proposar about why you wish to decline.

This is how you decline meeting from Freebusy.