I'm wondering, how did you uninstall the plugin? We believe it was not removed properly. Apparently the
redmine_intouch plugin was not uninstalled properly, as the MySQL table
settings_templates belongs to the plugin.
Did you create any backup or snapshot before applying the plugin? We strongly recommend creating backups in case issues like these happen. If you did, it can be restored easily.
If not, it might probably be easier to re-install Redmine, as the plugin does modify a lot of things. If this is not an option, you could try checking the files causing issues.
For instance, in the previous log,
settings.html.erb is causing HTTP 500 errors because of the Intouch plugin's customizations to that file, so you could try to empty (NOT delete, but remove all text inside it) from this file:
I hope it helps!