Through the Nelio Content Settings you can delete a Nelio Content social profile and thus prevent new social messages from being scheduled or the ones you had prepared from being published. However, Nelio Content will still have access to that social network, as you may have other websites that do have that profile set up and, therefore, need to publish messages.
To completely remove Nelio Content permissions in Tumblr and ensure that none of your websites has access to publish in Tumblr, sign in to your Tumblr account and select the Settings option. Then, click on Apps.

You will find the third party applications with access to your account. Click on the cross icon to remove Nelio Content’s access permissions to Tumblr. Of course, you can always give Nelio Content permissions again by connecting the profile.