started delete group function (see https://github.com/Project60/sepa_dd/issues/150)
worked on delete group function (see https://github.com/Project60/sepa_dd/issues/150)
worked on delete group function (see https://github.com/Project60/sepa_dd/issues/150)
Merge pull request #152 from systopia/issue_150

Delete group button (https://github.com/Project60/sepa_dd/issues/150)