Hi Mantas,
I am afraid that you can not remove the account, However, you can cancel the account. Please refer this
guide to check how cancellation works. Could you please enable the logs and share the complete SOAP request and response so that I can troubleshoot the ManagedCustomer limit issue. To enable the logs in the Java client library, please check this
guide. Guides in other languages can be found
here. You could also use 'Reply privately to author' option while responding.
Thanks,
Milind, AdWords API Team.