How to disable MPPE with PPTP (3.20)?

Currently I have several Mikrotik routers serving as PPTP VPN Servers for my clients (Windows machines (no problems with Linux clients)).
I want to disable MPPE encryption for client connections.
Under ppp profiles I’ve disabled encryption both in default profile & default-encryption profiles, but winbox shows that client connections are still encrypted. How can I solve my problem?
Also I’d like to know wheter RADIUS CoA is supported with PPTP (in part of dynamically changing QoS settings (rate-limits))?

got to solve this problem?