If you want to remove all HTML Content from a String with Oracle there is now a great function available in Oracle APEX 22.2!
APEX_ESCAPE.STRIPHTML ( p_string IN VARCHAR2 )
RETURN VARCHAR2 deterministic;
Before that you had to use something like regexp_replace to remove any HTML Tags from a string.
Check out the APEX Documentation for more Details: https://docs.oracle.com/en/database/oracle/apex/22.2/aeapi/STRIPHTML-Function-Signature-1.html#GUID-347F8DAD-5CC4-444C-A2C0-B102D1CC95FD
Imagine you have a Column based on a Rich-Text in Oracle APEX and you want to remove all HTML Code. The new function is a great way to get rid of the HTML Code.
Result as Plaintext vs apex_escape.striphtml()