The memorial was erected by party loyalists at Vallikkaad near Vadakara, where Chandrasekheran, a former CPI-M leader, was hacked to death in May 2012.
The memorial was found vandalised in the wee hours, police said.
Chandrasekheran floated RMP after he was dismissed from CPIM over differences with party leadership.
RSP leaders alleged that CPI-M activists were behind the attack. As a protest, the area observed a half-day hartal.
Twelve accused, including three CPI(M) leaders, had been convicted by a court in the Chandrasekheran murder case.