This is because you have invalid html, your each tr should have a unique id, so you need to use class, as when jquery will resolve the selector you applied it is just able to find the first row, so change in html to add it as class:
<table class="samplerow" style="display:none">
<tbody><tr class="fullrow">
<td><input type="text" id="txtuserid" /></td>
<td><input type="text" id="txtuname" /></td>
<td><input type="text" id="txtpass" /></td>
<td><input type="text" id="txtcpass" /></td>
<td><input type="text" id="txtfullname" /></td>
<td><input type="text" id="txtemail" /></td>
<td><button class="remove">Remove</button></td>
</tr>
</tbody></table>
and now in jquery apply class selector:
$(".fullrow").each(function () {
});