We can follow one of the two strategies below to remove outliers from a data frame having stings.
To remove outliers, we have to create a new data frame with only numeric columns and then remove all the outliers in this new data frame.
After that, we should concat the string data typed columns to our new data frame.
Remove outliers in the old data frame itself one column after another column.
Visit the following links to learn more about outlier detection and removal techniques: