SQL Server 2017

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create table temp
(
	alphanumeric varchar(100)
)
;
insert into temp
(alphanumeric)
values
('051 765 999'),
('MK00564123'),
('KJ786453425/9'),
('432563542/3'),
('096745632'),
('53452BMG441,8'),
('0000'),
('')


;
8 rows affected

CREATE FUNCTION dbo.udf_GetCleanedAlphaNumeric (@alphanumeric VARCHAR(100))
RETURNS TABLE
AS
    RETURN
      (SELECT SUBSTRING(cleaned, PATINDEX('%[^0]%', cleaned + 'x'), 8000) AS Final
       FROM   (VALUES (SUBSTRING(@alphanumeric, 1, PATINDEX('%[,;\/]%', @alphanumeric + ';') - 1))) ca1(prefix)
              CROSS APPLY (VALUES ( REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
			                        REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
									REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
									REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
									REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
									REPLACE(REPLACE(prefix, ' ', ''), 'a', '')
									, 'b', ''), 'c', ''), 'd', ''), 'e', ''), 'f', '')
									, 'g', ''), 'h', ''), 'i', ''), 'j', ''), 'k', '')
									, 'l', ''), 'm', ''), 'n', ''), 'o', ''), 'p', '')
									, 'q', ''), 'r', ''), 's', ''), 't', ''), 'u', '')
									, 'v', ''), 'w', ''), 'x', ''), 'y', ''), 'z', '') )) ca2(cleaned)) 
SELECT alphanumeric,
       Final
FROM   temp
CROSS APPLY dbo.udf_GetCleanedAlphaNumeric(alphanumeric)


alphanumeric
Final


051 765 999
51765999

MK00564123
564123

KJ786453425/9
786453425

432563542/3
432563542

096745632
96745632

53452BMG441,8
53452441

0000

alphanumeric	Final
051 765 999	51765999
MK00564123	564123
KJ786453425/9	786453425
432563542/3	432563542
096745632	96745632
53452BMG441,8	53452441
0000