use the delete [/force] [/recursive] [filesystem:]/file-url privileged EXEC command

/recursive  deleting a directory and all subdirectories and the files contained in it.

/force     suppress the prompting that confirms a deletion of each file in the directory.

example:

delete folder

delete file

os 15.0

1 Connect to console

2 Boot up the switch

3 Hold the MODE button for about 20 sec, then release it.

4 When the terminal display the following prompt  switch:

5 Type flash_init

6 Type dir flash:

7 delete flash:config.text and vlan.dat if they exist

8 Type boot (reload)

One can also use the following command to erase the configuration  (however, if Vlans is configured, vlan.dat has to be deleted as VLANs are not saved in the NVRAM, but in the flash in a totally independent file named VLAN.dat, write erase will not delete Vlan.dat)

switch# write erase  (or erase starup-config)
Erasing the nvram filesystem will remove all files! Continue? [confirm]y[OK]
Erase of nvram: complete
switch#
switch# reload

Note:  private-config.text is used for the switch when it is booted outside of a cluster in standalone mode.