Hi, My iPad is delivered for service, and I got a message that I should turn off the "Find my iPad" function. How do I do that remote? Best regards Michael

If sending your iPad for service, this support page should be self explanatory:

Get your iPhone, iPad or iPod touch ready for service – Apple Support

See this link for directions --> Remove a device from Find My iPhone on iCloud.com - Apple Support

I interpreted the OP as the device is already in for service and wasn't removed from Find My as was supposed to be done before sending it in. Hence the ask about how to do it remotely.

Good catch. If not performed prior to sending the iPad for service, this might well be the only way - after the fact - to avoid an unwanted return.