See Upload Fonts
Removing Font Families
At the top level (Font Families) click the "..." icon of a family, and choose "Delete".
A confirmation will be asked before you delete the font family. Deleting a font family might break existing templates.
Remove a Font Style
At the top level, click a font to see its styles.
At the styles level, click the "..." icon, and choose "Delete"
Confirm to delete the style. As with the font family, deleting even a single style might break existing templates.