Haven't tested the MikroTik HotSpot Manager, but what you refer to most probably is a Session-Timeout limit. This can be handled since a long time ago.
The main difference is if you can set the limit at login time (i.e. "stay online for max 1 hour" or "may transfer max. 1 GB of data") or if you want to connect a logged in user at your will. In the first case those limits are given to the RouterOS by (for example) RADIUS limits, which can be enforced by the router. In the second case, you have to create a new connection to the router telling it to disconnect user ABC. This has been realised in the newest betas for ppp-like connections (PPPoE, ...), but not for hotspot users.