You have the entry backwards. It would be:
$50k Debit Payroll Expense
$15k Credit Federal Withholding Tax Payable
$1k Credit Social Security Tax Payable
$6k Credit State Withholding Tax Payable
$28k Credit Cash
If you are on the cash basis of accounting, you adjust your income for receivables and payables, removing them to adjust to cash basis.
You cannot take a deduction for accrued payroll taxes if you are on the cash basis. You are only allowed to deduct what you actually pay.
Even if you are on the accrual basis of accounting, there are limitations to the items that you can deduct - for example, accrued bonuses have to be paid within 2 1/2 months of the end of the year. Also, accrued payroll for shareholders/owners are not deducted. There is an election that one can make if you are on the accrual basis of accounting to currently deduct prepaid expenses (instead of deducting them as used over the subsequent year). But this is for accrual basis, to basically put them on a cash basis for prepaids.
I hope this answers your question. If you have any more, please feel free to ask and I will be happy to answer.
Thanks! Have a great weekend!