Can I close all Outlook.com sessions that I have opened on different computers?

It would seem that I forgot to logout of my Hotmail account (on Outlook.com aka Login.live.com) on a comptuer at school.

Someone used this conenction to send unwanted e-mail.

Even though I changed the password, this other session still appears valid since the person can still send e-mail.

Can I remotely shut this session down (something similar to disconnect from everywhere) ?

You cannot invalidate the sessions remotely. However changing password helps. I am not sure how long would that take to get into effect.

You can review your activities here: https://account.live.com/Activity

Some security related options here: https://account.microsoft.com/security