Another case of hash avoidance, and no need for multiple split calls:

>perl -wMstrict -le
"my @testlist = qw(
   ctahci cptcsa0 ctsata:25:seed cptcsa1:50:seed ctsata_1:25:seed
   );
 my @removelist = qw(cptcsa0 ctsata cptcsa1);
 ;;
 my $remove = join ' | ', @removelist;
    $remove = qr{ $remove }xms;
 print $remove;
 ;;
 my @newlist = grep ! m{ \A $remove \b }xms, @testlist;
 print qq{'$_'} for @newlist;
"
(?^msx: cptcsa0 | ctsata | cptcsa1 )
'ctahci'
'ctsata_1:25:seed'
[download]

#!/usr/intel/bin/perl
use strict;
use warnings;
my @testlist = qw(ctahci cptcsa0 ctsata:25:seed cptcsa1:50:seed ctsata
+_1:25:seed);
my @removelist =qw(cptcsa0 ctsata cptcsa1);
my $outfile = "./new.list";

my %removehash=map{$_=>1} @removelist;

my @newlist=grep !defined( $removehash{ (m/(\w+)/)[0] }), @testlist;

# creating new list
open (my $OUTFILE, ">",$outfile) or die "Cannot open $outfile for writ
+ing:$!\n";

print $OUTFILE "$_\n" foreach (@newlist);
[download]

Adjust the regular expression to suite your requirements.

ur script is great, but my @testlist and @removelist may contain more than one word such as:

ctahci_sip11cs_devslp_deto_exp:50:seed
ctahci_sip11cs_devslp_deto_exp2:50:seed
[download]

therefore the code will assume it is same when one word is matching. How to deal with this?

You will need to test out the conditions you expect to work, and define your problem more clearly.

I tested the patterns you proposed with my code - it works fine.

If it does not meet your requirements, as I said in my previous post - feel free to modify the regular expression to work with your requirements.

             I hope life isn't a big joke, because I don't get it.
                   -SNL

I don't understand, especially where you say

... @removelist may contain more than one word such as:
ctahci_sip11cs_devslp_deto_exp:50:seed
ctahci_sip11cs_devslp_deto_exp2:50:seed


The string  'ctahci_sip11cs_devslp_deto_exp:50:seed' doesn't look like anything appearing in the  @removelist array in your OPed example code. Can you give an example of data for which NetWallah's code fails?

After the several tries. This code just perfect for me. Thanks a lot. =)

Omit building the hash and try the following grep that uses smart matching:

@newlist = grep !((split /:/)[0] ~~ @removelist), @testlist;
[download]

Output:

ctahci
ctsata_1:25:seed
[download]

Update:

NetWallah provided excellent fixes for your code, and it generates your desired output. You may still, however, use the above grep that doesn't use a hash.

this is no working. syntax error at "]~"

The smart match operator ( ~~ ) was introduced in perl-5.10, so you'll need perl newer than 5.10 if you want to try it

but i want to have the :25:seed and :50:seed in my outputlist.