Remove section numbers latex
<p>I have a problem with section numbering in latex. I want to remove the section numbers from headings and contents but I want the numbers to be there for lemmas, theorems etc. I want it to look like:</p>

<pre><code> Section Whatever
   Some unimportant text.

 Section Whatever else
   Another unimportant text.
   Lemma 2.1
   Theorem 2.2 

 Section Whatever again
   Theorem 3.1
</code></pre>

<p>How can I do it? I tried </p>

<pre><code> \renewcommand\thesection{}
</code></pre>

<p>but it removes the numbers even from lemmas and theorems. Thank you very much :) </p>