Hi usamafromzakariya,
Regarding removing a device from your Apple ID it sounds like the device was offline and Activation Lock may not have been turned on. The information below found in the article here has details for the requirements needed to remove a device. Remove a device from Find My on iPhone - Apple Support
"Remove a device from your Devices list
If you’re not planning on using a device, you can remove it from your Devices list. The device must be offline in order for you to remove it.
The device appears in your Devices list the next time it comes online if it still has Activation Lock turned on (for an iPhone, iPad, iPod touch, Mac, or Apple Watch), or is paired with your iOS or iPadOS device (for AirPods or Beats headphones).
- Do one of the following:
- For an iPhone, iPad, iPod touch, Mac, or Apple Watch: Turn off the device.
- For AirPods: Put AirPods in their case and close the lid or turn the AirPods off.
- For Beats headphones: Turn off the headphones.
2. In Find My, tap Devices at the bottom of the screen, then tap the name of the offline device.
3. Tap Remove This Device, then tap Remove."
Additionally, if someone else has your information they can "... turn off Activation Lock and remove the device from your account by turning off the Find My [device] setting on the device."
Losing a device is never easy, be sure to follow the steps here for your compromised account: If you think your Apple ID has been compromised
You can also alert your cellular carrier and local law enforcement. If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support
Best.