Step 1: Choose and delete Sequence(s) from Followup Sequences app in the Configuration Workspace

Configuration Workspace --> Followup Sequences App --> 

    Open the sequence you wish to delete --> Open Actions drop-down menu --> choose delete

Step 2: Modify template and delete as an option in the Sequences field from The Seller Leads app in the Main Workspace 

Main Workspace --> Seller Leads App --> Open any Seller Lead item --> Modify template --> 

    scroll to sequence field --> hover selected category option to delete until 'x' appears --> click 'x' to delete