How data is deleted?
So, your answer to this question will be like just go the specific location in your system and delete the desired file/folder. After deleting it from your PC it will move to recycle bin and then if we want to permanently delete the data then just simply delete the deleted file/folder from recycle bin also and that's it, the data is gone now. Wait......... Actually it is not true. The data is still there in your system. Yes, I am not kidding let's understand the logic behind it.
Let's understand with an example
Consider the storage like a Book.
So a book is a container containing different lessons/chapters along with an index. Here index plays an important role. So in index part of Book, there is a list of which lessons/chapters the book is containing. And if any lesson/chapter is not listed in that index then it means the book doesn't contain that lesson/chapter. Similarly, Consider your system's storage as an index and the data inside it as lesson/chapters. Now let's assume that some part of your system's storage is filled with some data hence the details of the data will be mentioned to the storage(in which part the data is stored) i.e in the form of index. And then you want to delete the data to free up space of your storage. So you deleted the data from that specific path and the deleted date is now moved to recycle bin. Then you also deleted the data from recycle bin and your storage is free now and you are thinking that your data is gone but wait...... Actually the data hasn't gone anywhere it is still there in your system and it can be recovered easily by using some 3rd party software/tools.
Let me explain...
So the thing is that after deleting data from recycle bin it is erased from index of system's storage i.e the system now will not be able to recognize that there is any data at that part of storage but the data still exit.
How to delete data permanently?
After reading above lines you would ask that how to delete data permanently form the system. So the straight forward answer to this question is that "Data can't be deleted permanently". Don't be surprised it is partially true but there are some way to overcome it to some extend. So if you want to delete data from your device then after deleting it from recycle bin i.e. add some other data to the same part of storage from where you have deleted the data earlier. So by doing this the previously stored data will be overwritten by new data and in this way you can delete you older data to some extend. So this is a way to delete data however it is also not much accurate/efficient.
Solution to permanently delete data
The one and only way to delete data permanently is to destroy/smash the Hard Disk Drives(HDDs) or Solid State Drives(SSDs) physically.
This is the only solution to completely delete data from you device.
I Hope the above information was helpful to you.