Teamflect fetches all your calendar items and identifies your 1-on-1 meetings. From time to time, there can be meetings that you don't want to appear inside of Teamflect - placeholder agenda items and vacation agenda items can be examples of these types of meetings you may want to remove from Teamflect.
Find that meeting in Teamflect and click the "..." icon at the top left.
Click "Remove this from the meetings list". If the meeting you removed is a recurring meeting, all the instances will be removed from Teamflect.
As an alternative, you can also click the "Not a 1-on-1?" button inside the 1-on-1 meeting reminder notification that you receive 24 hours before the 1-on-1 meeting time.