Dear Erdimanni,
Welcome to our FEFLOW community. :)
You can make an elemental selection for the entire domain or for a subdomain of interest. You can use this selection to [b]Refine Elements[/b] or to [b]Derefine Elements[/b]. Both options are provided by the [b]Mesh toolbar[/b]. Please note that you cannot derefine a mesh if you did not refine it before. In this situation you need to generate the mesh again by adopting a smaller number of desired elements.
Best regards
Björn
