General Wrangel made a last ditch effort for the White Army in Crimea but was defeated in November 1920. The Civil War soon finished after this.

Why did Lenin and Trotsky win the Civil War?

Trotsky and the Red Army: Trotsky disciplined the army well and was a skilled strategist. By 1920, the Red Army was five million strong and trained better than the Whites.
Weakness of the White Armies: the Whites were disunited, poorly led and uncoordinated. Their soldiers were also prone to drunkenness and looting.
War Communism: Lenin established policies that equipped the army well with food and weapons.
Propaganda: Communists frightened peasants with the idea that Tsarist rule would return with the victory of the Whites.
Peasant Attitudes: The peasant population were more concerned about the Whites rather than the Communists.
Allied Withdrawal: With the loss of interest in Russia, Allied forces gradually withdrew. Weapons supply dried up and the Whites became less effective.