วีซ่าทำงานในอาบูดาบี

Keeping a freelance visa while working full-time for a company: No, this is not permitted in the UAE. A full-time role requires a company-sponsored work visa, and working under a freelance visa for a full-time employer would be non-compliant.
Cancelling the freelance visa but keeping the freelance licence: Yes, this is allowed. You may cancel the freelance visa, move to the company's employment visa, and retain the freelance licence (subject to the issuing authority's rules on operating without a visa).