The selector has to be ONE string... So the coma separator for multiple selectors has to be inside the string.
This snippet works:
let $cid = 1
jQuery('#t_'+$cid + ', #'+$cid).remove();
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="t_1">t_1</div>
<span id="1">1</span>
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