It could be nice to have … session manager…

Notepad++ already natively supports sessions¹: File > Save Session… and File > Load Session… allow you to save and load any session files you want.

However, one feature you mentioned was

with a menu to delete unwanted files entries

The native session handling does not allow you to pick-and-choose which tabs end up in a session file. However, the session files are XML-based, so once the session file is saved, you can open it as a text file, and delete any unwanted entries from the session file, and save the file. The next time you Load Session, it will not include the extra tabs².

There is a plugin called Session Manager that may have more features of use to you: go to the Plugins menu, Plugins Admin entry, and install Session Manager. I don’t use named sessions much, so I don’t know all the features of that plugin, but if you’re regularly using sessions, I’ve heard it’s a good improvement.

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1. Official sessions docs @ https://npp-user-manual.org/docs/session/ . As of 2020-Dec-02, the npp-user-manual.org version of the session docs is rather scant. There is an improvement coming soon, which can be viewed on github while waiting for it to be published.

2. Caveat: when you File > Load Session…, it will add all the tabs from the session file to the current instance of Notepad++: it doesn’t automatically close other files, so you may have to File > Close All if you only want the session’s tabs open and don’t want other tabs to stay open.

You can already save/load sessions, so what is the difference you are suggesting?