When an employee chosen to resign, they have made the decision to move on.
Sometimes, employers often find that the employee's work performance and/or general attitude at work reduces, they can become distracted or disruptive towards their colleagues, lateness or just be absent without informing you. Sometimes as the employer you have to decide if they should continue to attend work as it is no longer beneficial for the needs of the business.
3 options:
1.
Have
a word with the employee as this sometimes improve the situation.
2.
Decide
if you ask the employee to leave and pay them in lieu of their notice period.
3.
Place
the employee on garden leave.
It is always beneficial for the employer to have comprehensive contracts of employment to clearly set out the terms of employment.