The samples are useful for testing purposes if run into an issue, we can ask you to place one of those test files into a timeline and proceed.
As for where your media resides, the default can be changed to whatever folder you wish. The setting is in PREFERENCES.
Unfortunately, the last setting, is the new "default", so each time you switch from one project to another, you need to tell PD the proper place to direct your files, or your Christmas video items might wind up in Aunt Edna's funeral video folder.
As for the inability to delete, I dunno.
HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
Nvidia GTX 960(4GB)/16GB DDR3/
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5.
Tape capture using 6 VCR, TBC-1000, Elite BVP4+, Sony D8 camcorder with TBC.
https://www.facebook.com/BarryAFTT