uninstall – Remove directory from a saving .gen file using grep command

I have used the grep command to match a pattern then the matching row has saved in a file. But when saved the result it’s saved with the file directory. But I want to save only the row result not the directory.

my command :
grep -r ‘rs689 ‘ $TMP_DIR/ >> $GEN_FILE

and output of the genotype file is like that:

impute-out/tmp_impute2:SNP1298 rs689 2182224 A T 1 0 0
impute-out/tmp_impute2_info:SNP1298 rs689 2182224 A T 0.000 1.000 1.000 2 0.000 0.000 -1.000
impute-out/tmp_impute2_haps:SNP1298 rs689 2182224 A T -1 -1
impute-out/tmp_impute2:SNP4568 rs12722495 6097283 T A 0 0 1
impute-out/tmp_impute2:— rs12722495 6097283 T C 0.250 0.500 0.250

I want to save the output in this file like :

SNP1298 rs689 2182224 A T 1 0 0
SNP1298 rs689 2182224 A T 0.000 1.000 1.000 2 0.000 0.000 -1.000
SNP1298 rs689 2182224 A T -1 -1

Please suggest me how to remove the directory when saving the file. or Is there any regular expression to use in grep command which will remove directory during save the result?

Thanks in advance