Yes.  The Purezone can be removed from the spa for a short period of time, i.e. when you are cleaning the interior of the spa, from a few hours to even longer periods of time as long as the proper steps are taken. 

To avoid damaging the Purezone device and the cassette, here is what you should do when removing the Purezone from your spa:  

• Go to any hardware store and purchase a 1-gallon bucket.  
• Fill the 1 gallon bucket with water about 3/4 full
• Remove the Purezone from the spa
• Place the Purezone in the bucket so the lab unit (where the cassette is) is covered in water.  The Purezone battery pack can hang over the side of the bucket.

After you are through cleaning the spa:

• Remove the Purezone from the bucket
• Replace the Purezone in the spa making sure that the metal tab on the lab unit is facing towards the spa and not towards the back of the spa
• Dispose of the water in the bucket

Note:  This is a good time to ensure that you are keeping the spa clean and free of pollen, dust, debris and containments so that the Purezone can work properly.  See here for more information.