Trump revokes security clearance from ex cia chief over erratic behaviour

I think you may be mistaken. It was actually former CIA Director John Brennan who had his security clearance revoked by President Trump in 2018, not the other way around.

On March 12, 2018, President Trump announced that he was revoking Brennan's security clearance, citing "erratic behavior" and "lying" about the Russia investigation. Brennan had been a vocal critic of Trump and had spoken out about the president's actions and policies.

Brennan responded to the decision by saying that it was a "sad and tragic" move that was "designed to punish an individual for speaking the truth about the President and his administration."

It's worth noting that the decision to revoke a security clearance is typically made by the Department of Justice or the Department of Defense, not the President. However, as President, Trump has the authority to revoke security clearances under certain circumstances.

In this case, Trump cited Brennan's "erratic behavior" and "lying" about the Russia investigation as the reasons for revoking his clearance. However, many critics argued that the decision was politically motivated and an attempt to silence a vocal critic of the President.