modify the framing of input selection in html

You can remove that line by disabling the outline property.

The first of the inputs I have removed the outline while the second I left it by default.

Example:

#texto{
  outline: none;
}

.texto{
   border-radius: 15px 10px 15px 10px;
}
  

<form>
  <input id="texto" value="SinOutline" class="texto">
  <input value="ConOutline" class="texto">
</form>

If what you would like is for a line to appear around the edge similar to the one shown with the outline property, you could simulate a outline using the box-shadow property otherwise.

Example:

#texto{
   outline: none;
   box-shadow: 0px 0px 4px red;
}

.texto{
   border-radius: 15px 10px 15px 10px;
}

<form>
    <input id="texto" value="SinOutline" class="texto">
    <input value="ConOutline" class="texto">
</form>

There is the possibility of giving the property "rounded", but only in the browser firefox, possibly in the future becomes standard. You can read more about this here: link

If you want to eliminate it for aesthetics you can do it like this:

.clase_input:focus{
    outline:0px;
}