Del Line if specific issue

Shell Programming and Scripting
1

HI Guys

I have below input :

PO 121255 SorkO_RM_,rlsmel=310_410_3_11104_43831
PO 125564 SorkO_RM_,rlsmel=007G43823

I want delete line which have "_" after = Sign

Output :

PO 125564 SorkO_RM_,rlsmel=007G43823
2 
grep -v "=.*_" file
3 
cat file
PO 121255 SorkO_RM_,rlsmel=310_410_3_11104_43831
PO 125564 SorkO_RM_,rlsmel=007G43823

sed -i '/.*=.*_/d' file

cat file
PO 125564 SorkO_RM_,rlsmel=007G43823