Can a Proclamation be revoked at any time by the President?
Yes, a Proclamation can be revoked at any time by the President. This is stated in clause (7) which says "the President shall revoke a Proclamation issued under clause (1) or a Proclamation varying such Proclamation if the House of the People passes a resolution disapproving, or, as the case may be, disapproving the continuance in force of, such Proclamation." This implies that the President has the power to revoke a Proclamation at any time upon receiving a resolution from the House of the People.