However, if I deleted the folder from "database maintance" page and view the folder again, the folder will be back to the database
The database editor delete folder possibility exists not to "hide" the folder from the database, but to enable folder refresh with a new DiskTree scan.
If you don't want a folder indexed, just add it to the list of excluded folders, under Database>IndexerSettings, and never manually select it again from the DiskTree. If included for scan just because the subfolder options is on, it will be excluded if in exclude list.
I hope you can give user an option to auto/manually add folder to database. It will be better if I can build more than 1 database too.
I suppose these are pré-imposed ideas you have from using other softwares. That's not the idea behind PDFE. This idea is to have all PDFs, and CHMs, whenever they are (hard drives, network places, removable medias, etc.), indexed in the database and later use program functionalities to manage that data. The multiple databases idea can be accomplished by virtual collections, functionality that will be developed in a future version.
if what you are trying to accomplish is a way to define what folders are served by the web interface, take a look to the groups settings of the Web Interface users and permissions. There you can easily define what folders a particular user can have access too. And to hide from all users, and from GUI DB scan modes results, just uncheck that folder at the database editor.
And, I believe you should improve the "database maintance" page. Each sub folder is 1 line now and all under a main drive. I can't imagine while I have thousands folders and sub folders, and I need to delete some folder locations.
Can't agree more. I really need to reformulate that tree. Even so, the current implementation has the advantage that's more easy to delete only one folder, without ask if user also want to delete its sub-folders.