When creating a new form that will be filled out on a Group contact, the form result will by default show you all group members in that group and allow you to select the Participants that may be associated with that form result:
By selecting these Participants, you create linked records of the form result on these participants' profile. You can learn more about how filling out group form results work here!
If you have a form where selecting Participants is not relevant, you can choose to hide this box from the form in the Form Builder settings:
Simply click the option to Hide Participants and save your form by clicking Save Changes.
When your users create a new form or edit an existing form, they will no longer see the blue Participants box: