unset

Example

Destroy variables:

 <span class="token php language-php"><span class="token delimiter important"><?php</span>  
<span class="token variable">$a</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"Hello world!"</span> <span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"Delete the value of the previous variable &#39;a&#39;: "</span> <span class="token operator">.</span> <span class="token variable">$a</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span>  
<span class="token keyword">unset</span> <span class="token punctuation">(</span> <span class="token variable">$a</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"The value of the variable &#39;a&#39; after deletion: "</span> <span class="token operator">.</span> <span class="token variable">$a</span> <span class="token punctuation">;</span>  
<span class="token delimiter important">?></span></span>

Try it yourself