$re = '/-.*/';
$str = 'es-
af
af-NA
af-ZA
agq
agq-CM
ak
ak-GH
am
am-ET
ar
ar-001
ar-AE
ar-BH
ar-DJ
ar-DZ
ar-EG
ar-EH
ar-ER
ar-IL
ar-IQ
ar-JO
ar-KM
ar-KW
ar-LB
ar-LY
ar-MA
ar-MR
ar-OM
ar-PS
ar-QA
ar-SA
ar-SD
ar-SO
ar-SS
ar-SY
ar-TD
ar-TN
ar-YE
as
as-IN
asa
asa-TZ
ast
ast-ES
az
az-Cyrl
az-Cyrl-AZ
az-Latn
az-Latn-AZ
bas
bas-CM
be
be-BY
bem
bem-ZM
bez
bez-TZ
bg
bg-BG
bm
bm-ML
bn
bn-BD
bn-IN
bo
bo-CN
bo-IN
br
br-FR
brx
brx-IN
bs
bs-Cyrl
bs-Cyrl-BA
bs-Latn
bs-Latn-BA
ca
ca-AD
ca-ES
ca-FR
ca-IT
ccp
ccp-BD
ccp-IN
ce
ce-RU
cgg
cgg-UG
chr
chr-US
ckb
ckb-IQ
ckb-IR
cs
cs-CZ
cy
cy-GB
da
da-DK
da-GL
dav
dav-KE
de
de-AT
de-BE
de-CH
de-DE
de-IT
de-LI
de-LU
dje
dje-NE
dsb
dsb-DE
dua
dua-CM
dyo
dyo-SN
dz
dz-BT
ebu
ebu-KE
ee
ee-GH
ee-TG
el
el-CY
el-GR
en
en-001
en-150
en-AG
en-AI
en-AS
en-AT
en-AU
en-BB
en-BE
en-BI
en-BM
en-BS
en-BW
en-BZ
en-CA
en-CC
en-CH
en-CK
en-CM
en-CX
en-CY
en-DE
en-DG
en-DK
en-DM
en-ER
en-FI
en-FJ
en-FK
en-FM
en-GB
en-GD
en-GG
en-GH
en-GI
en-GM
en-GU
en-GY
en-HK
en-IE
en-IL
en-IM
en-IN
en-IO
en-JE
en-JM
en-KE
en-KI
en-KN
en-KY
en-LC
en-LR
en-LS
en-MG
en-MH
en-MO
en-MP
en-MS
en-MT
en-MU
en-MW
en-MY
en-NA
en-NF
en-NG
en-NL
en-NR
en-NU
en-NZ
en-PG
en-PH
en-PK
en-PN
en-PR
en-PW
en-RW
en-SB
en-SC
en-SD
en-SE
en-SG
en-SH
en-SI
en-SL
en-SS
en-SX
en-SZ
en-TC
en-TK
en-TO
en-TT
en-TV
en-TZ
en-UG
en-UM
en-US
en-US-POSIX
en-VC
en-VG
en-VI
en-VU
en-WS
en-ZA
en-ZM
en-ZW
eo
es
es-419
es-AR
es-BO
es-BR
es-BZ
es-CL
es-CO
es-CR
es-CU
es-DO
es-EA
es-EC
es-ES
es-GQ
es-GT
es-HN
es-IC
es-MX
es-NI
es-PA
es-PE
es-PH
es-PR
es-PY
es-SV
es-US
es-UY
es-VE
et
et-EE
eu
eu-ES
ewo
ewo-CM
fa
fa-AF
fa-IR
ff
ff-CM
ff-GN
ff-MR
ff-SN
fi
fi-FI
fil
fil-PH
fo
fo-DK
fo-FO
fr
fr-BE
fr-BF
fr-BI
fr-BJ
fr-BL
fr-CA
fr-CD
fr-CF
fr-CG
fr-CH
fr-CI
fr-CM
fr-DJ
fr-DZ
fr-FR
fr-GA
fr-GF
fr-GN
fr-GP
fr-GQ
fr-HT
fr-KM
fr-LU
fr-MA
fr-MC
fr-MF
fr-MG
fr-ML
fr-MQ
fr-MR
fr-MU
fr-NC
fr-NE
fr-PF
fr-PM
fr-RE
fr-RW
fr-SC
fr-SN
fr-SY
fr-TD
fr-TG
fr-TN
fr-VU
fr-WF
fr-YT
fur
fur-IT
fy
fy-NL
ga
ga-IE
gd
gd-GB
gl
gl-ES
gsw
gsw-CH
gsw-FR
gsw-LI
gu
gu-IN
guz
guz-KE
gv
gv-IM
ha
ha-GH
ha-NE
ha-NG
haw
haw-US
he
he-IL
hi
hi-IN
hr
hr-BA
hr-HR
hsb
hsb-DE
hu
hu-HU
hy
hy-AM
id
id-ID
ig
ig-NG
ii
ii-CN
is
is-IS
it
it-CH
it-IT
it-SM
it-VA
ja
ja-JP
jgo
jgo-CM
jmc
jmc-TZ
ka
ka-GE
kab
kab-DZ
kam
kam-KE
kde
kde-TZ
kea
kea-CV
khq
khq-ML
ki
ki-KE
kk
kk-KZ
kkj
kkj-CM
kl
kl-GL
kln
kln-KE
km
km-KH
kn
kn-IN
ko
ko-KP
ko-KR
kok
kok-IN
ks
ks-IN
ksb
ksb-TZ
ksf
ksf-CM
ksh
ksh-DE
kw
kw-GB
ky
ky-KG
lag
lag-TZ
lb
lb-LU
lg
lg-UG
lkt
lkt-US
ln
ln-AO
ln-CD
ln-CF
ln-CG
lo
lo-LA
lrc
lrc-IQ
lrc-IR
lt
lt-LT
lu
lu-CD
luo
luo-KE
luy
luy-KE
lv
lv-LV
mas
mas-KE
mas-TZ
mer
mer-KE
mfe
mfe-MU
mg
mg-MG
mgh
mgh-MZ
mgo
mgo-CM
mk
mk-MK
ml
ml-IN
mn
mn-MN
mr
mr-IN
ms
ms-BN
ms-MY
ms-SG
mt
mt-MT
mua
mua-CM
my
my-MM
mzn
mzn-IR
naq
naq-NA
nb
nb-NO
nb-SJ
nd
nd-ZW
nds
nds-DE
nds-NL
ne
ne-IN
ne-NP
nl
nl-AW
nl-BE
nl-BQ
nl-CW
nl-NL
nl-SR
nl-SX
nmg
nmg-CM
nn
nn-NO
nnh
nnh-CM
nus
nus-SS
nyn
nyn-UG
om
om-ET
om-KE
or
or-IN
os
os-GE
os-RU
pa
pa-Arab
pa-Arab-PK
pa-Guru
pa-Guru-IN
pl
pl-PL
ps
ps-AF
pt
pt-AO
pt-BR
pt-CH
pt-CV
pt-GQ
pt-GW
pt-LU
pt-MO
pt-MZ
pt-PT
pt-ST
pt-TL
qu
qu-BO
qu-EC
qu-PE
rm
rm-CH
rn
rn-BI
ro
ro-MD
ro-RO
rof
rof-TZ
ru
ru-BY
ru-KG
ru-KZ
ru-MD
ru-RU
ru-UA
rw
rw-RW
rwk
rwk-TZ
sah
sah-RU
saq
saq-KE
sbp
sbp-TZ
se
se-FI
se-NO
se-SE
seh
seh-MZ
ses
ses-ML
sg
sg-CF
shi
shi-Latn
shi-Latn-MA
shi-Tfng
shi-Tfng-MA
si
si-LK
sk
sk-SK
sl
sl-SI
smn
smn-FI
sn
sn-ZW
so
so-DJ
so-ET
so-KE
so-SO
sq
sq-AL
sq-MK
sq-XK
sr
sr-Cyrl
sr-Cyrl-BA
sr-Cyrl-ME
sr-Cyrl-RS
sr-Cyrl-XK
sr-Latn
sr-Latn-BA
sr-Latn-ME
sr-Latn-RS
sr-Latn-XK
sv
sv-AX
sv-FI
sv-SE
sw
sw-CD
sw-KE
sw-TZ
sw-UG
ta
ta-IN
ta-LK
ta-MY
ta-SG
te
te-IN
teo
teo-KE
teo-UG
tg
tg-TJ
th
th-TH
ti
ti-ER
ti-ET
to
to-TO
tr
tr-CY
tr-TR
tt
tt-RU
twq
twq-NE
tzm
tzm-MA
ug
ug-CN
uk
uk-UA
ur
ur-IN
ur-PK
uz
uz-Arab
uz-Arab-AF
uz-Cyrl
uz-Cyrl-UZ
uz-Latn
uz-Latn-UZ
vai
vai-Latn
vai-Latn-LR
vai-Vaii
vai-Vaii-LR
vi
vi-VN
vun
vun-TZ
wae
wae-CH
wo
wo-SN
xog
xog-UG
yav
yav-CM
yi
yi-001
yo
yo-BJ
yo-NG
yue
yue-Hans
yue-Hans-CN
yue-Hant
yue-Hant-HK
zgh
zgh-MA
zh
zh-Hans
zh-Hans-CN
zh-Hans-HK
zh-Hans-MO
zh-Hans-SG
zh-Hant
zh-Hant-HK
zh-Hant-MO
zh-Hant-TW
zu
zu-ZA';
$subst = "";
$result = preg_replace($re, $subst, $str, 1);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php