Log into your Splashtop Account management page at my.splashtop.com.
Mouse over your account address at the top right and select Account Info.
In order to delete your Splashtop account, any existing subscriptions to your Splashtop Account need to be turned off and expired. (Account Info -> Subscriptions)
Shut down your Splashtop Business team (Account Info -> Team) if you are the team owner, or "remove myself from this team" if your are a team member (Account Info -> Account Summary).
Once your account is not associated with a Splashtop team, you can delete your Splashtop Account at Account Info -> Account Summary.