Research your state$$s laws for maintaining data to determine the appropriate timeframe for the archive. Then, create a policy that addresses the following points. You can find policy templates online or create your own but it must include the following:

What data will be archived?

Identify examples of clinical data, administrative data and demographic data

How will the data be archived?

Examples could be external hard drives, cloud servers, discs, flash drives, etc.

Where will the archived data be stored?

Onsite? External company? Storage locker?

How will the data be protected?

Passwords? Secure storage

How long will the data be archived before it is destroyed?

Again, refer to state laws and other requirements