In Windows: to 'disable' a specific User interface plugin (e.g View Manager) try this:
- open the Configuration directory by pressing the button in Prefs->Misc
- open the plugins folder
- tack .save on the end of the relevant plugin zip -- e.g. rename to View Manager.zip.save
- restart calibre
To restore the plugin do that again, except in step 3 remove the
.save.
I have File Explorer configured to show file extensions.
BR