Uninstalling Order Manager (M2)
From a command line in the Magento root folder run:
bin/magento module:disable Fooman_OrderManager bin/magento setup:upgrade composer remove --update-with-dependencies fooman/ordermanager-m2
If you have used the Manual Installation Method (Option 2), then please delete the following files if they exist.
rm vendor/fooman/packages/Fooman_OrderManager*.zip