Much more information needed.
If you are trying to sell then are you the mortgagee in possession?
If you hold a charge, what ranking of charge do you have (first, second, charging order?).
Who has the benefit of the caution and why?
If a mortgagee in possession has a right of sale then certain interests (I'm not saying this is one of them) can be disregarded and the sale is done under a different form of transfer (TR2) and able to be registered at the Land Registry.
This is a guidance booklet but it's more for practitioners. See, in particular, 3.2.9 "Cautions in the proprietorship register".
You should obtain proper legal advice from someone who has all information available to them.