i want to delete what after the : in this data (the password) and let just the emails
[emails] https://i.sstatic.net/dX9RB.png
You would be looking at apply.
I think a solution like this:
def remove_pw(x): #define your custom function
y = x.split(":") #simple way to split on the colon
return y[0] #return only the first part which is the email
df = yourdata
new_df = df['email'].apply(remove_pw)
According to your image: ( I am assuming that what is shown is named df and is a valid pandas dataframe.)
new_df = df['kobastal@yahoo.com:raskolnik'].apply(remove_pw)