deleting feature in design tree not working

Hi, I have solidworks student 2020 SP3.0 and have been unable to delete features i have created. For example, I would design a part and started a sketch on a body and then wanting to delete that sketch i right click and click delete. At this moment, slideworks freezes and does not work. The only thing that works is pressing ESC and it cancel the delete procedure. please help with this.