How set a filter for a specific folder, after selecting duplicates?

When I search for duplicates (in different folders), I only want to remove the duplicates of a specific folder afterwards.
My question is whether I can apply a filter to see only this specific folder?

What I do is:

  1. I'm searching for duplicates (in different folders).
  2. After the search I select the duplicates.
  3. When the duplicates are selected, I label the duplicates in the color blue.

Now I just want to remove the duplicates from a specific folder. I just don't know if it's possible and how to set a filter for a specific folder.
So what I want is to set a filter to a specific path (=folder). If this is possible, and I can set a filter to see only that specific folder, I just have to remove the blue labeled ones from it (the blue labeled ones are the duplicates). This way I have only deleted duplicates from this folder.

You can use Edit > Select By Pattern > Advanced to select things based on their full path or location. (Location = full path, minus the filename on the end.)

(Note that Full Path and Location filtering/finding is broken in the current beta, but works in 12.14 and will be fixed before 12.15 is released.)

Or, another approach, if the labels have already been applied then you can use Tools > Find Files > Advanced to search below the desired folder for everything with the Blue label.

Regarding to "Select By Pattern".
Is there a way to delete the name from created filters in the drop-down menu?
When I have deleted the filter through the button "clear", the filter names still remain visible in the drop-down menu. Over time this can give a long list of names of non-existent filters (cleared filters).

Clear just clears the current window. It doesn't affect what's saved.

You can remove saved filters via Preferences / File Operations / Filters.