In TurboTax Online, search for “T10” on the Tax Home page to get to that slip.

The T10 slip is issued by an RPP administrator or DPSP trustee and used by CRA to help determine an employee's RRSP deduction limit for the year. If you used Auto-fill, the T10 may have come in that way. You might want to check your CRA MyAccount or with your employer before deleting it.