Hi Martin,
Sorry to hear the trouble that you are having. We had a similar situation when I was working for a real estate co here in Dubai. The tenant didn't pay his rent, the contract expired but he didn't leave. Unfortunately it is not legal to simply enter the apartment even though you own it. This could actually make things worse if the tenant was to claim against you for example.
At that time, we opened a case at the police due to the bounced cheque but this was not enough to get them to act. I believe you may need to submit all the papers and contracts, Ejari etc at RERA rent committee and they will give a ruling on this. It will however depend on whether the correct notice to vacate was given to the tenant (12 months served officially - based on the fact that you wish to sell).
I am not a practising lawyer in Dubai so the information provided is only my opinion from my experiences in this market!
Good luck with it!
