Yuri Lijm, 66, hired a crane and drove it to Audentes University. He then removed two statues of Soviet World War II heroes and delivered them to the Estonian History Museum.
One of the monuments commemorates Soviet cadets of the Tallinn military school, and the other is a statue of the founder of Estonia's Communist party, Hans Poogelmann.
"I came here to do this because it is the responsibility of a citizen of Estonia. If the authorities are so helpless, I have to do this myself. It is our holy duty," Lijm said in a TV interview.
"Estonia still has too many these socialist monuments. I will definitely not stop until I clean Estonia of them. A period of cleaning out the trash has been declared in Estonia. I am cleaning out the red trash," he said.
Last spring, Lijm publicly threatened to blow up the Bronze Soldier statue in central Tallinn, but was later acquitted by a court.
Relations between Russia and Estonia, a European Union member since 2004, hit a low-point in April last year after Estonian authorities relocated the Bronze Soldier, a Soviet-era war monument, from central Tallinn and disinterred the remains of soldiers ahead of Victory Day, which is marked on May 9 in Russia. Over 1,000 people were arrested in protests against the move, and one Russian was killed.
During the dispute, the Estonian government accused the Kremlin of orchestrating a series of mass cyber-attacks that disabled the websites of Estonia's parliament, leading banks, ministries, broadcasters and newspapers.
The latest dispute between the two countries has been over the trial of an 88-year-old Soviet war hero, Arnold Meri, accused of genocide in Estonia. Russia's State Duma adopted on Friday a declaration calling on the European Union to halt the trial, saying it the charges are fabricated and politically motivated.