Every person, before receiving the license aforesaid, shall enter into a bond in the sum of five thousand dollars ($5,000) with sureties to the approval of the City Manager, conditioned that he will indemnify and save harmless the City from all accidents, liability and damage of every kind and nature caused by his negligence either in the execution of or protection of his work or for any unfaithfulness or inadequate work done under and by virtue of his license and that such licensee will comply with all ordinances of the City and all rules and regulations now in force or hereinafter provided. The City Manager may revoke any license for any violation of any of the ordinances of the City or for the violation of any rules and regulations or for any cause which the City Manager may deem just and proper.