There are two ways to manage your fonts in MainType. You can use virtual groups or keep-in-sync folders.
A virtual group doesn’t really contain the fonts, but it uses a database. It takes only a couple of bytes to add a font to a group, so hardly uses disk space.
On the other hand you can use keep-in-sync folders, which is basically how fonts actually reside on your hard drive. If you have exactly the same font in two folders, it will store the font twice as well.
So if you want to categorize your fonts and expect to have the same font in several places, then it is strongly recommended to use virtual groups. If you wish to work within a folder structure you also want to access through your hard drive, then keep-in-sync folders might work best.
So first decide if you want virtual groups or keep-in-sync folders. If you wants virtual groups then just add and delete as much as you please. If you want to use keep-in-sync folders, then within MainType go to the specific folder and then select font you wish to delete. You will then be able to choose the option to delete the font from the file system folder.