How to replace data from specific column only in spark scala

Input:

Output:

Solution:

#excaclty we read file first

val df = spark.read.format("csv").option("header","True").load("file:///D:/idname.txt")

df.show()

#here, we choose fname column for change string data 'Shah' to null

val result_df = df.withColumn("fname",when(col("fname")==="Shah",null).otherwise(col("fname")))

result_df.show()