转载：https://blog.51cto.com/304514244/1555230
方法1：
开机状态下
F3-2F#erase startup-config
Erasing the nvram filesystem will remove all configuration files! Continue? [confirm]
[OK]
Erase of nvram: complete
*Mar 1 00:04:19.946: %IP_SNMP-4-NOTRAPIP: SNMP trap source FastEthernet0/1 has no ip address
*Mar 1 00:04:21.204: %SYS-7-NV_BLOCK_INIT: Initialized the geometry of nvram
F3-2F#reload
Proceed with reload? [confirm]
*Mar 1 00:04:44.893: %SYS-5-RELOAD: Reload requested by console. Reload reason: Reload command
*Mar 1 00:04:44.902: %IP_SNMP-4-NOTRAPIP: SNMP trap source FastEthernet0/1 has no ip address
Boot Sector Filesystem (bs) installed, fsid: 2
Base ethernet MAC Address: cc:d5:39:02:80:00
Xmodem file system is available.
The password-recovery mechanism is enabled.
Initializing Flash...
flashfs[0]: 539 files, 19 directories
flashfs[0]: 0 orphaned files, 0 orphaned directories
flashfs[0]: Total bytes: 32514048
flashfs[0]: Bytes used: 13510144
flashfs[0]: Bytes available: 19003904
flashfs[0]: flashfs fsck took 11 seconds.
...done Initializing Flash.
done.
方法2：
未开机状态下
开机，按mode键后，在如下的switch:提示符后输入
switch:flash_init
switch:rename flash:config.text flash:config.old
switch:boot
启动后就没了
方法3：
开机状态下：
按住mode键，在所有指示灯闪烁过后松开，一般是10-15S左右，即可恢复初始状态