Depends on which way you like it most.
margin-right: 100%;
.btn-danger{
margin-right:100%;
}
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<form method="POST" action="{{route('admin.projects.destroy',$project->id)}}" onsubmit="return ConfirmarBorrarProyecto()">
<a href="{{ route('admin.project.edit', $project->id)}}" class="btn btn-success btn-sm" id="margindata">Edit</a>
<input type="submit" value="Delete" class="btn btn-danger btn-sm" id="margindata">
<input type="hidden" name="_token" value="{{Session::token()}}">
</form>
position: relative;
.btn-danger{
position:relative;
top:30px;
left:-47px;
}
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<form method="POST" action="{{route('admin.projects.destroy',$project->id)}}" onsubmit="return ConfirmarBorrarProyecto()">
<a href="{{ route('admin.project.edit', $project->id)}}" class="btn btn-success btn-sm" id="margindata">Edit</a>
<input type="submit" value="Delete" class="btn btn-danger btn-sm" id="margindata">
<input type="hidden" name="_token" value="{{Session::token()}}">
</form>
display: block
@Pablo version
.btn-danger{
display: block !important;
}
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<form method="POST" action="{{route('admin.projects.destroy',$project->id)}}" onsubmit="return ConfirmarBorrarProyecto()">
<a href="{{ route('admin.project.edit', $project->id)}}" class="btn btn-success btn-sm" id="margindata">Edit</a>
<input type="submit" value="Delete" class="btn btn-danger btn-sm" id="margindata">
<input type="hidden" name="_token" value="{{Session::token()}}">
</form>
And more sure ways exist, it will always depend on where and how you want to present them, container or adjacent elements.