How to sell a property which has a high court stay order on it?

In such a case you can file an application for urgent hearing of the matter, or whenever next listed to request the court for fast disposal, bringing before the court your financial requirements.

 
Secondly, the most important thing in situation of a stay it is recommended and adviced strictly to abide with the orders of the court, else you will attract contempt of court proceeding that will be initiated against you.

There is no way you can proceed with sale, one option is filing an application for vaccation of stay but with the property beind a subject matter of dispute,  cant be sold as no buyer would want to go ahead in such a scenario.

On the other hand,  i will advise you that property matters are very critical and sensitive and there must be some escape but for that the documents need to be carefully studied.

Please ensure to talk to your advocate before every hearing and keep your self posted.