If you're sure you want to proceed, just follow the rules, send the itemized list within proper time frame to last known address, deduct security deposit plus any required interest they've accrued, showing the balance due, then give them a deadline for payment or your terms for a payment plan, and see what happens.  

Out of curiosity, J., if you don't mind me asking, what is your long term exit strategy from the flipping business?

Just out of curiosity, has many of you found it to be a good arena to sale and wholesale your properties?

@Gene Hacker, you had curiosity but now you have my attention.  

I have 7 rental properties and have accrued cash in the bank.

Assuming that the property would rise with typical inflation at 3%, your ROI with principal accrued, $0 cash flow, and 3% appreciation would be ~$8k a year (~12%).  

I've seen spreadsheets with people showing 50% expenses but never a breakdown of how they accrue that cost.

From IRS Pub 535: You can generally deduct as a business expense all interest you pay or accrue during the tax year on debts related to your trade or business.

That way you can learn the business, the ins and outs, study your area, and if you begin to accrue a clientele, you will earn commission significantly higher than w2 income typically can provide should you go all in.

Recorded on the right side of the balance sheet, liabilities include loans, accounts payable, mortgages, deferred revenues and accrued expenses.When holding title with a mortgage still outstanding, you have both an asset (the equity in the property) AND a liability (the mortgage to be paid)