MySQL 8.0

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select version();

version()

8.0.30

create table macs
(
macaddress varchar(20)
);

insert into macs values('90CCAADD3341');

insert into macs values('90:3f:ff:11:22:33');

insert into macs values('33:44:aa:bb:34:6a');

insert into macs values('8801abcd3231');

select macaddress, upper(replace(macaddress,':','')) as new_macaddress
from macs;

macaddress
new_macaddress

90CCAADD3341
90CCAADD3341

90:3f:ff:11:22:33
903FFF112233

33:44:aa:bb:34:6a
3344AABB346A

8801abcd3231
8801ABCD3231

macaddress	new_macaddress
90CCAADD3341	90CCAADD3341
90:3f:ff:11:22:33	903FFF112233
33:44:aa:bb:34:6a	3344AABB346A
8801abcd3231	8801ABCD3231