Installing then removing the Episerver.Marketing.Testing nuget package will not remove the associated Marketing Test Monitor scheduled job. To avoid the logs filling up with the following error, see below.
System.IO.FileNotFoundException: Could not load file or assembly 'EPiServer.Marketing.Testing.Web' or one of its dependencies. The system cannot find the file specified.
File name: 'EPiServer.Marketing.Testing.Web'
Run the following query against the database to disable the scheduled job.
update tblScheduledItem
set enabled = 0
where name = 'Marketing Test Monitor'