CSS

remove bootstrap button outline

.btn{
	box-shadow: none !important
}

how to remove bootstrap button outline

. btn:focus {
outline: none;
box-shadow: none;
}

bootstrap button outline

<button type="button" class="btn btn-outline-primary" href="#">Primary</button>

button outline bootstrap

Button-bootstrap

<button type="button" class="btn btn-outline-primary">Primary</button>
<button type="button" class="btn btn-outline-secondary">Secondary</button>
<button type="button" class="btn btn-outline-success">Success</button>
<button type="button" class="btn btn-outline-danger">Danger</button>
<button type="button" class="btn btn-outline-warning">Warning</button>
<button type="button" class="btn btn-outline-info">Info</button>
<button type="button" class="btn btn-outline-light">Light</button>
<button type="button" class="btn btn-outline-dark">Dark</button>

how to remove bootstrap button outline

.btn{
	box-shadow: none !important
    /* this how we remove bootstrap button outline */
}