Categories: Why are all email folders categories? How to use mail categories?

I use categories to identify received emails, like ‘Quotes’, ‘Technical’, ‘Financial’, etc.
I also use quite a number of sub-folders to sort my email.
Since using eMClient V7, all my folders, sub folders show under categories, completely messing up my original intend, and the function of categories.
I need subfolders to sort out received emails, independent from categories.
How to seperate the two functions?
If I delete all sub-folder categories, will this delete the actual subfolders of my emails?

Please explain clearly how this works in eMClient V7

Deleting categories through Menu > Tools > Categories, will not delete the emails. All it will do is remove the category from the email, leaving them where they are.

When using Gmail IMAP, this will work slightly differently, because each category is additionally displayed as an IMAP folder. Deleting the category will remove the email from that folder, but it will still be in it’s original folder, and any other folders for which it has a category.

Thanks Gary, please let me rephrase my question, please see attached picture
I am using Imap setting in eMClient.
Looking at eMClient only, not Gmail, I created many subfolders to keep these organized (column on the left).
Selecting a message from any (sub)folder, then right-click to categorize shows a list of categories with a tick box in the first category ticked being the folder path (or name). I do not want all these folder names showing in my categories, as my actual categories are below ‘More >’, like ‘Quotations’.
Why are all my folder names listed under ‘Categorize’, how to remove these without losing my folder structure?

As showing below, I have set up my categories showing only the categories I need:

When receiving a message in my inbox, selecting this to assign a category (categorize) does not reflect the list above but includes all path names. I do not want to see these, while I cannot remove these as they do not show under categories . . .

On the server, Gmail actually only has three folders: All Mail, Trash and Spam.

The folders you created in eM Client appear as folders in the application, but on the server they are in fact only labels - not real folders. So Gmail labels appear in eM Client as folders, and are also listed as categories. They are the same thing.

Categories you create in eM Client are just categories, until you assign one to a Gmail email. Then they also become labels in Gmail and folders in eM Client. That is why the Donations category you created also shows as a folder in Gmail.

Does that make sense?

Gerard-- Gmail has only one actual folder (save for junk and trash) which is “All mail”.  It uses categories to emulate folders and as Gary mentioned, they are displayed as folders in eM Client.  There is no distinction between folders and categories, which is why you see them listed together.