Usually, failing back is part of a DR test. If you decide to remove the secondary's, and rebuild them, will that be considered a successful DR test?
Are your concerns about the log files growing based upon baselines you have captured, or a best guess? Is the worry that you will run out of space, or that the logs will take a long time to catch up, making the fail back take a significant amount of time?
Also, in the DR test, is activity going to be at a "normal" level? Will the users be doing the same level of activity on the databases? I'm guessing that it will be far less, making the log growth also smaller.
As an example, I have 1.3 TB of databases in our production system. The "worst" database for log growth is between 80 and 120 GB per day, depending upon the day of the week.
We had to fail over to our DR site a few weeks back. Connectivity to the 2 servers in the primary DC was down for 2 days. When the servers came back online and the data started syncing again, it took less than 40 minutes for the data be synced up. The disks that hold the log files were never in any danger of filling up.
So, my answer is leave the logs grow. That being said, assuming that you are fairly certain that they will not fill the disks.