Good. Feel free to rate which ever reponse was useful - for others who might follow ... although ... 2 cents about that ... the ohoo plugins show to be compat up to versions 2.5 ot 2.6 of Moodle. How did they get into a 3.4? Something in 3.4 should have 'whoopied' upon installation and not allowed installation to begin with.
In addition to making backups, also advise checking the 'moodle store' for plugin compatibility to your version of Moodle ... and don't try to fit a 'square peg into a round hole' ... no sledge hammer, please ... for your own sake!
And if you upgraded the site from a 2.5/6 all the way to 3.4 still check plugin compat for destination version compat. Remove the plugins *before* the march ... don't wait until after arriving at destination version thinking one can remove ... as you have just experienced, me thinks. ;)
'spirit of sharing', Ken