Hi K Barnes - check and confirm how the secured loan is registered as that can make a difference as to how to apply to have it removed -
Search for land and property information - GOV.UK
When a company is dissolved, its property (including any charges) usually becomes "bona vacantia," meaning it passes to the Crown. You should check with Companies House or other relevant authorities to confirm the lender has indeed been dissolved and whether the company's assets have passed to bona vacantia.
Contact Bona Vacantia who may then provide consent for discharge if they determine that no money is owed under that charge.
Bona Vacantia - GOV.UK
Land registration is complex, designed to protect legal and financial interests in property. There can be significant consequences for any error. Please consider seeking legal representation. Before making an application without legal representation, it is important to consider the benefits of using a conveyancer.