Hello Linda Jeider,
They are correct, just deleting data to the recycle bin, data could be recovered technically.
You must wipe your hard drive’s free space to prevent deleted files from being recovered. You can download a tool called CCleaner to do so by clicking here.
Once you have the program installed, you can perform the following.
Method 1 – Automatically wipe when cleaning:
In CCleaner, click the Custom Clean icon on the left.
In the Windows tab, scroll to the Advanced category (shown with an ! icon) and select the Wipe Free Space checkbox.
CCleaner displays a warning about extra time. Click OK.
Run CCleaner as usual.
Note: You need to specify settings for the feature to run correctly. To do this:
Go to Options > Settings
Under Wipe Free Space drives, confirm which drive(s) you wish to wipe.
You can also confirm if you want CCleaner to Wipe MFT Free Space
Link to wiping a disk’s free space from Piriform.