--- a/testing/profiles/profile
+++ b/testing/profiles/profile
@@ -173,22 +173,17 @@ def diff(a, b, fmt, limit_key):
     results['delete'] = {k: v for sym, pref in symbols for k, v in pref.items()
                          if sym.label == 'delete'}
 
     same = set(prefs_a.keys()) - set(chain(*results.values()))
     results['same'] = {k: v for k, v in prefs_a.items() if k in same}
     return format_diff(results, fmt, limit_key)
 
 
-def sort_file(path):
-    """Sort the given pref file alphabetically, preserving preceding comments
-    that start with '//'.
-
-    :param path: Path to the preference file to sort.
-    """
+def read_with_comments(path):
     with open(path, 'r') as fh:
         lines = fh.readlines()
 
     result = []
     buf = []
     for line in lines:
         line = line.strip()
         if not line:
@@ -199,22 +194,31 @@ def sort_file(path):
             continue
 
         if buf:
             result.append(buf + [line])
             buf = []
             continue
 
         result.append([line])
+    return result
 
+
+def sort_file(path):
+    """Sort the given pref file alphabetically, preserving preceding comments
+    that start with '//'.
+
+    :param path: Path to the preference file to sort.
+    """
+    result = read_with_comments(path)
     result = sorted(result, key=lambda x: x[-1])
     result = chain(*result)
 
     with open(path, 'w') as fh:
-        fh.write('\n'.join(result))
+        fh.write('\n'.join(result) + '\n')
 
 
 def sort(profile):
     """Sort all prefs in the given profile alphabetically. This will preserve
     comments on preceding lines.
 
     :param profile: The name of the profile to sort.
     """
@@ -231,16 +235,38 @@ def show(suite):
 
     :param suite: The name of the suite to show preferences for. This must
                   be a key in suites.json.
     """
     for k, v in sorted(read(suite).items()):
         print("{}: {}".format(k, repr(v)))
 
 
+def rm(profile, pref_file):
+    if pref_file == '-':
+        lines = sys.stdin.readlines()
+    else:
+        with open(pref_file, 'r') as fh:
+            lines = fh.readlines()
+
+    lines = [l.strip() for l in lines if l.strip()]
+    if not lines:
+        return
+
+    def filter_line(content):
+        return not any(line in content[-1] for line in lines)
+
+    path = os.path.join(here, profile, 'user.js')
+    contents = read_with_comments(path)
+    contents = filter(filter_line, contents)
+    contents = chain(*contents)
+    with open(path, 'w') as fh:
+        fh.write('\n'.join(contents))
+
+
 def cli(args=sys.argv[1:]):
     parser = ArgumentParser()
     subparsers = parser.add_subparsers()
 
     diff_parser = subparsers.add_parser('diff')
     diff_parser.add_argument('a', metavar='A',
                              help="Path to the first profile or suite name to diff.")
     diff_parser.add_argument('b', metavar='B',
@@ -256,15 +282,21 @@ def cli(args=sys.argv[1:]):
     sort_parser = subparsers.add_parser('sort')
     sort_parser.add_argument('profile', help="Path to profile to sort preferences.")
     sort_parser.set_defaults(func=sort)
 
     show_parser = subparsers.add_parser('show')
     show_parser.add_argument('suite', help="Name of suite to show arguments for.")
     show_parser.set_defaults(func=show)
 
+    rm_parser = subparsers.add_parser('rm')
+    rm_parser.add_argument('profile', help="Name of the profile to remove prefs from.")
+    rm_parser.add_argument('--pref-file', default='-', help="File containing a list of pref "
+                           "substrings to delete (default: stdin)")
+    rm_parser.set_defaults(func=rm)
+
     args = vars(parser.parse_args(args))
     func = args.pop('func')
     func(**args)
 
 
 if __name__ == '__main__':
     sys.exit(cli())