Follow the below steps to transfer AWS EC2 instance from one account to another account:

• Log into your AWS management console of source account and navigate to EC2.
• Select the instance and click on Actions drop-down menu, hover on the image, and click Create Image. 
  
  
• A Create Image window appears. Fill the details Image name, Image description, and click on Create Image.
  
  

  

  Note: There is a checkbox No reboot; by default, the checkbox is not selected, which means when the image is taken, the Instance will not be restarted. And if this checkbox is selected, the Instance will be restarted.

• The time taken to create an image depends on the instance type and the size of the EBS volume of the instance.
• Click on Images drop-down and select AMIs to view the status of your image.
  
  

  

• Once the AMI status is updated to Available status, you can share the AMI with your target AWS account.
• Select the AMI to be shared. Click on Actions drop-down menu, and click Modify Image Permissions.
  
  

  

• A Modify Image Permissions window appears.
  
  

  

• Add the target AWS account number to AWS Account Number and click on Add Permission. Refer to the article Your AWS Account ID and its Alias to find your AWS Account Number.
  
  

  Note: To share the AMI with multiple accounts repeat this step until all the target account numbers are added.

• To allow the create volume permissions for the snapshots, select Add “create volume” permissions to the following associated snapshots when creating permissions.
• Click on Save.
  
  

  

• Log in to the AWS management console of the Target Account.
• Navigate to EC2 and select the region in which the AMI was created in the Source Account.
  
  

  

• Select AMI from the Images and filter options to Private Images. The default filter option is Owned by me.
  
  

  

• The shared AMI will be visible
• As the AMI is available in the target account, now you can launch an EC2 instance using this AMI.
• The launch wizard appears. The same steps are to be followed as we do while launching an EC2 instance.