How do I deduct a charge from a tenants bond?

To show a deduction from a tenants bond the process will depend on how you have the security deposit lodged; for the example below we have used a carpet cleaning charge for illustration purposes:

DPS Deposits (Custodial Scheme)
==================
The process for returning a deposit lodged with the DPS is detailed in the following entry of the online user manual:

http://helpdesk.rentpro.co.uk/entries/20892287-return-of-security-deposit-from-deposit-protection-scheme

In this case you'll obviously be retaining part of the deposit, i.e. the cost of the carpet cleaning.

You should raise and progress a Trouble Ticket in the normal way for the carpet cleaning. The cost of this will by default be applied to the landlord account associated with this property. To credit the landlord account for the cost of the carpet cleaning add an EXPENSE, via the Fees / Expenses tab on the property, with a NEGATIVE value. (Enter an appropriate description)

My Deposits/ Tenancy Deposit Scheme (Insurance based scheme)
============
Similar to the DPS process you should still raise a Trouble Ticket for the works involved and credit the landlord account using an expense with a negative value on the property as above.

Prior to returning the deposit apply a tenant fee of type EXPENSE to the tenant to cover the cost of the carpet cleaning. This process is detailed in the following entry of the online user manual:

http://helpdesk.rentpro.co.uk/entries/20372222-apply-a-tenant-fee

Then process the return of the security deposit as detailed in the following entry of the online user manual:

http://helpdesk.rentpro.co.uk/entries/20377508-return-of-security-deposit

You'll note that when you select a Payment Type of 'Return of Security Deposit' within the Payments tab (Tenant Transactions) that the outstanding fee / expense is listed. Click on the 'Deduct All' button below this fee to deduct the outstanding fee from security deposit that you are currently holding. Process the remainder of the payment details in the usual fashion.