changing my device to a new account

Yes, you can transfer your AWS Elemental Link device from one AWS account to another. This is a supported feature that makes it easy to transfer device control to a different account, which is particularly useful in situations like yours where the original account owner has left the organization.

The process involves transferring the Link device from the previous account to your account. Since this is specifically about AWS Elemental Link devices, this is different from transferring other AWS resources like EC2 instances or AMIs, which would require different procedures.

To proceed with the transfer, you'll need access to both the source account (the one currently controlling the device) and your destination account. If you don't have access to the source account because the person left, you may need to work with your IT department to gain appropriate access to that AWS account first, or contact AWS Support for assistance with the transfer process.

AWS Elemental Link devices are designed to be transferable between accounts to accommodate exactly these types of organizational changes.
Sources
AWS Elemental Link FAQs

Hello.

Can you sign in to the source AWS account?
If you can sign in to the source AWS account and have been granted the appropriate IAM permissions, you should be able to migrate by following the steps outlined in the following AWS blog.
https://aws.amazon.com/jp/blogs/media/awse-how-to-transfer-aws-elemental-link-between-aws-accounts/
https://aws.amazon.com/jp/blogs/media/awse-how-to-transfer-aws-elemental-link-between-aws-regions/