You can remove the "Powered by Promolayer" logo by toggling a switch in the content editor. This feature is available on any paid plan.
Steps
Upgrade to any paid plan if you have not already done so.
Open the content editor for the display you want to edit.
Toggle the "Powered by Promolayer" logo switch to the off position.
Any displays created after upgrading to a paid plan will have this switch automatically disabled and the logo will not display by default.