Myanmar's ex-ambassador in London spent Wednesday night in his car after saying he was locked out of his embassy.
Kyaw Zwar Minn said staff were asked to leave the building by Myanmar's military attaché, and he was dismissed as the country's representative.
British Foreign Secretary Dominic Raab has condemned the "bullying actions," but the UK has accepted the change.
Myanmar's military seized power in a coup on 1 February, sparking protests and escalating violence.
Kyaw Zwar Minn has criticised the military coup, and called for Myanmar's ousted leader Aung San Suu Kyi to be released.
About 600 people - including dozens of children - have been killed so far as pro-democracy protesters demand a return to power of elected leader Ms Suu Kyi and her National League for Democracy (NLD) party.