To remove them so you can see all your folders click on the settings icon on the top right (see below).
The click on Chat and Meet on the menu bar.
To switch off the Meet and Hangout menus on the left select Off for Google Chat (Hangout) and Hide the Meet section in the main menu.
If there are folders you do not need, for example if you are setup for IMAP then you will have extra folders like below beginning with [imap]. To hid these clip on the 3 dots beside the folder when your mouse hovers over it. Select 'Hide' under 'In label list' and the folder will no longer be visible in the top list but can still be accessed by clicking on 'more' on the bottom of the list to see all the folders.