Hi DisTerp,
Welcome!
I have removed many Sunline valances during camper restorations and may be able to help.
What year and model is your camper, and which valances do you want to remove? Pending the model/floor plan there mount a few different ways they put the screws in to hold them on. Knowing which you want to take off, I can help better explain.
If you or someone else you know has access to sewing, consider upgrading the old valances. My wife made new covers and covered the existing ones to brighten the room. We did the original upgrade in 2008, and now she is considering a refresh. She does a camper project with fabric and yarn, and I use wood and steel. We made our Sunline our own to meet our wants and needs.
This is the front bedroom upgrade.
Looked like this when we bought this camper, our 2004 T310SR.
After the wife's handiwork.
We also redid the wallpaper strip at the ceiling; this pic was before the upgrade. We had to change that strip after the new curtains.
The new ceiling wallpaper.
Even a matching ceiling cushion cover.
I hope this helps give you some ideas.
John