I made a withdrawal from an RESP that was 100% after tax contributions and was charged 1/6 of the withdrawal as a transaction charge. Is that amount a tax deduction?

Ok, so I had an RESP $137.90 and withdrew it all, have t4a slip, what do I do with it?

You obviously withdrew the taxable interest portion so that would be why you got a T4A.  It must be pretty small on $137.90 but you'd have to report it on your tax return.

No.  Contributions, transaction fees and any other fees charged in respect of as an RESP are not deductible.