Remove special char in string

Question

I have this string:

$str = '<div class="titre-liste">23.zzerze& erezrzeràr ezrezr àrez éé </div>
&mdash; Ұ₭₱∅Δ (@Zykprod) <a href="https://twitter.com/Zxsqdd/status/xxxx">4 avril 2017</a></blockquote>
<script async src="//platform.twitter.com/widgets.js" charset="utf-8"></script></center>
<br /><br />';

And what I want is to remove those kind of characters:

Ұ₭₱∅Δ 

I try to convert my string with utf8_encode , filter_var but I don't think it is the solution.