A model letter for saying you won't comply
Several points to address

In January, Montgomery County Public Schools in Maryland sent a letter to the community saying they wouldn't comply with one of POTUS's executive orders.
You may have to write something similar. Here's a model, based on Montgomery County's letter.
Address your letter to the community or the people you serve.
Provide information that touches on these points in a specific and helpful way:
- We recognize certain concerns in the current situation.
- Everyone, regardless of identity or background, deserves to receive the best.
- We stand by you, and we'll uphold our values.
- We'll pursue legal action if we must.
- We insist on keeping local authority over our own work.
- We'll actively support and fight for our staff.
- We recognize your rights.
- We'll stay focused on what we do every day, which is serving your needs.
Sign the letter and consider providing a way to contact you so everyone knows who's accountable.
If you want to ask your elected leader not to comply
Relatedly, some people like to call their reps or believe it's important to do so. Suppose you've got an issue like this (as it appeared back in December, before the inauguration):
Trump confirms that he plans to deport US citizens who have undocumented parents
— Aaron Rupar (@atrupar.com) 2024-12-08T15:20:44.266Z
Assuming you speak to the rep's staffer or leave a voicemail for the staffer, here's what you could say. You can state your specific concern, principle, and specific request. For example:
Thank you for picking up. My name is [NAME] and I'm a constituent who lives in [CITY, ZIP].
I heard Trump has said he will deport undocumented families along with their U.S. citizen children.
I'm calling to urge [REP'S NAME] to publicly refuse to cooperate with Trump's illegal deportation plans, including refusing to collaborate with ICE. I believe that's [REP'S NAME] responsibility as a leader and a human being.
Thanks for your attention to this critical matter.
(I've based this script on one provided by someone else a while back. That person has since deleted their post for reasons unknown to me, so I haven't named them here in case they do not wish to be named.)