In [23]: df1
Out[23]: 
  Name    income
0    a        $1
1    b    $2,000
2    c   $10,000
3    d  $140,000

In [24]: cols_to_change = ['income']

In [25]: for col in cols_to_change:
    ...:     df1[col] = df1[col].str.replace('[$,]', '')
    ...: 

In [26]: df1
Out[26]: 
  Name  income
0    a       1
1    b    2000
2    c   10000
3    d  140000