You own the property and you have every right to inspect it. You would post a 24 hr notice on the front door that you will be doing an inspection. I would not go thee alone bring someone along as a witness. Now if there is more to the story than you are saying then by all means follow your attorney's instructions but by law you are allowed access to your property. Are the utilities still in his name or have they been changed out? This may give a hint to if he is still there. Not sure how someone can sue you for harassment if you are not bothering them non stop. One inspection is not harassment nor can you trespass on your own property. If he has nothing left in the place and the utilities are not in his name then there is no reason to proceed with an eviction as far as I can see. The attorney may have a monetary reason for you to go forward though.