If you’re hoarding old devices, then it’s time to get rid of them. Old devices often contain software that is no longer supported with updates, and therefore vulnerable to cyber-attacks.
If your device is not supported any more, then dispose of it sensibly. You can check if it’s supported here: www.endoflife.date
To dispose of a personal device, simply remove your log-in accounts from it and restore it to its factory settings. You can then either sell the device or dispose of it in an appropriate manner.
If you think your device contains sensitive data, there’s special guidance here for disposal: www.ncsc.gov.uk/guidance/secure-sanitisation-storage-media