you can safely delete mods from extensions folder yes, if I understand you correctly. If your save is blocked because a mod has been removed then Azalrion's post should be followed. Once loaded save the game again and XR will remove other remnants from the save file and you are as clean as possible to play again. Be aware that traces can still remain and will still invalidate your save if posted for tech support.
X Rebirth - A Sirius Cybernetics Corporation Product
Split irritate visiting pilot with strange vocal patterns.
note that some Mods may not be removable from a Savegame. thats the reason why the save-attribute exists in the content.xml - if its set to true consider the Mod to be not removeable (if its false just remove it and if its not set at all you have to try using the method described above)
if not stated otherwise everything i post is licensed under WTFPL
Ich mache keine S&M-Auftragsarbeiten, aber wenn es fragen gibt wie man etwas umsetzen kann helfe ich gerne weiter
I wont do Script&Mod Request work, but if there are questions how to do something i will GLaDly help
Also you should ask the author or read the mod's topic if there is any uninstallation instruction. Some of them might ask you to edit your files, some other might ask you to do something in-game (like Capital Ship Bridge which shouldn't be uninstalled while being inside a ship) or even to use an external removal tool (like Mission Computer).
In my opinion this is even more important than looking at the "save" attribute. For example my mod is marked as being safe, but you have to do something to uninstall it properly.