Hi,
Try:
CONSTANTS: c_tab TYPE abap_char1 VALUE cl_abap_char_utilities=>horizontal_tab .
CONSTANTS: c_crg TYPE abap_char1 VALUE cl_abap_char_utilities=>cr_lf .
CONSTANTS: c_nln TYPE abap_char1 VALUE cl_abap_char_utilities=>newline .
*----------------------------------------------------------------------*
FORM clean_string
CHANGING
string .
REPLACE ALL OCCURRENCES OF c_tab IN string WITH ' ' .
REPLACE ALL OCCURRENCES OF c_crg IN string WITH ' ' .
REPLACE ALL OCCURRENCES OF c_nln IN string WITH ' ' .
ENDFORM . "clean_string
*----------------------------------------------------------------------*
Regards.