Answer
The standard deviation decreases from $6.44$ to $6.18.$
Work Step by Step
The standard deviation is a measure of dispersion of the data from the mean. The extreme data items (the smallest and the greatest) are the farthest from the mean, so they add the most to the variability.
Removing an extreme data item will decrease variability, so the standard deviation will decrease.
Checking with our spreadsheet calculator, let's remove the maximum age of $64$ and invoke the "Descriptive Statistics" feature (see image below).
The standard deviation decreases from $6.44$ to $6.18.$
