i have false alert that spam all my log file of snort how can i
disable this rule:

[**] [1:402:7] ICMP Destination Unreachable Port Unreachable [**]
[Classification: Misc activity] [Priority: 3]
02/05-14:51:36.448330 x.x.x..x.x > x.x.x.x
ICMP TTL:48 TOS:0x0 ID:60609 IpLen:20 DgmLen:68
Type:3 Code:3 DESTINATION UNREACHABLE: PORT UNREACHABLE
** ORIGINAL DATAGRAM DUMP:
x.x.x.x.x -> x.x.x.x.x
TCP TTL:54 TOS:0x0 ID:2497 IpLen:20 DgmLen:40 DF
Seq: 0x99DEB0B6
(12 more bytes of original packet)
** END OF DUMP

[**] [1:402:7] ICMP Destination Unreachable Port Unreachable [**]
[Classification: Misc activity] [Priority: 3]
02/05-14:51:36.448759 x.x.x.x.x -> x.x.x.x.x
ICMP TTL:48 TOS:0x0 ID:60610 IpLen:20 DgmLen:68
Type:3 Code:3 DESTINATION UNREACHABLE: PORT UNREACHABLE
** ORIGINAL DATAGRAM DUMP:
x.x.x.x..x -> x.x.x.x..x
TCP TTL:54 TOS:0x0 ID:2498 IpLen:20 DgmLen:40 DF
Seq: xxxx
(12 more bytes of original packet)
** END OF DUMP

Rule with SID 402 is in /etc/snort/rules/icmp-info.rules, see /etc/snort/threshold.conf for how to suppress it.

in /etc/snort/threshold.conf

i see this:
Suppress this event completely:

i should do that ?
1)Suppress this event completely: ICMP Destination Unreachable Port Unreachable

If you want to, yes. Use the rules Snort Id (SID), not the trivial name.