i want to delete repeated rows in dataframe in a for loop

i want to generate graphs from the dataframe by comparing few columns, but as it comparing each time with other rows, many graphs are plotted with same data, i need to avoid them

i have tried removing multiple data using df.drop but its shows the error "ValueError: Need to specify at least one of 'labels', 'index' or 'columns'"

for evt in range(len(df3)): if count < len(df3):

    count = count+1
    machine_name = df3.iloc[i,j]
    machine_number_filtered = df3.iloc[i,j]
    parameter_name = df3.iloc[i,k]
    axis_name = df3.iloc[i,l]
    i = i+1
    n = df3[df3['Machine'].str.contains(machine_name) & df3['Parameter'].str.contains(parameter_name) & df3['Axis'].str.contains(axis_name)] 

    n.plot(x='Date', y=['Values', 'Critical Limit','Warning Limit' ], figsize=(25,15), grid=2, linewidth = 7, marker = 'o', markersize = '10')

But it prints with set of graphs repeating everytime which is equal to similar rows