Government tribunal ruled Thursday that Erias Lukwago is guilty of abuse of office, incompetence and misconduct.
Announcement from Uganda pol comes during trial of Kenya's deputy president.
Move comes day of Kizza Besigye's planned launch of new anti-government demonstrations.
Museveni has now held power in Uganda for 27 years, making him one of Africa's longest-serving leaders.
Daily was pressured to reveal how it obtained politcally sensitive letter.
The rogue military commander faces arrest upon his return to Uganda.
The ouster is apparently linked to turmoil over Museveni's alleged plan to have his son succeed him as head of state.
Fury over a general's letter is challenging President Museveni's reputation as a moderate leader.
Latest twist in saga of a senior army officer accused of harboring presidential ambitions.
A general is accusing the president of trying to ensure his son replaces him as the country's leader.
