Mr Sam-Sumana had shown a willingness to abandon the vice-presidency by seeking asylum, it added.
On Saturday, Mr Sam-Sumana said he had asked for asylum in the US because his life was in danger.
The governing party had earlier expelled him after accusing him of fuelling violence, which he denies.
The dispute between President Ernest Bai Koroma and Mr Sam-Sumana has raised fears about the future stability of Sierra Leone.
Out of hiding
The West African state has been badly affected by the Ebola outbreak in the region, and is still battling to recover from a civil war which ended in 2002.
Government troops surrounded Mr Sam-Sumana’s home in the capital, Freetown, on Saturday.
He came out of hiding on Monday, telling journalists at his home: “I am safe. We are all safe.”
Correspondents say Mr Koroma’s decision could be challenged, as many people believe the constitution does not give him the power to sack the vice-president.
However, Mr Koroma said on Monday that he had “constitutional authority” to dismiss Mr Sam-Sumana, AFP news agency reports.
The governing All People’s Congress expelled him earlier this month, and accused him of trying to form a breakaway party in his home district of Kono.
The US State Department said on Sunday it was in contact with Sierra Leone’s authorities in an attempt to resolve the crisis.