Can you switch to drill orders after volunteering for recruiter?

As you mentioned "drill orders", are you referring to being an AGR Recruiter for the USAR or ARNG? Your profile says active duty Army so there's a disconnect as well as other issues impacting.

The primary factor is if you were accepted into the recruiting program, not if you've been to school yet. Once you've been selected and entered into the program (regardless if it was by volunteering or being voluntold), you're fenced off from other assignments and the CG, HRC would have to approve your release prior to the initial 3-year detail period.

If you haven't been accepted into the program and submitted a packet, you can contact USAREC or your career manager (depending how you submitted the packet and which process you used) and ask them to withdraw the packet from consideration.
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https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN30357-AR_601-1-000-WEB-1.pdf

Expectation management:
You do meet the minimum requirements for DSS.
The minimum is 1yr in E5 and BLC complete (I assume you did complete BLC) .
The selection criteria includes successive NCOERs that demonstrate potential to succeed as a senior (E7-E9) NCO. You just don't see that on E5 NCOERs.
You won't be selected if there are enough viable E6 candidates from DA select and volunteers.

That said, if you have orders for Recruiting school, you would have to be accepted to DSS to get those deleted.