Whenever an insurance certificate is required by this chapter the applicant shall file with the City Clerk a certificate of insurance showing: a) that the limits are at least as high as required, b) that coverage is effective for at least the license term approved, and c) that such insurance will not be cancelled or terminated without thirty (30) days' written notice served upon the City Clerk. Cancellation or termination of such coverage shall be grounds for license revocation. (1988 Code § 5.12)